Russia said Syrian President Bashar al-Assad presented reform plans on Tuesday to help end the bloodshed in Syria, but Western and Arab states acted to isolate Assad further as his forces resumed bombarding the protest hotbed of Homs.

Russian Foreign Minister Sergei Lavrov held talks with Assad in Damascus on a solution to the crisis palatable to Moscow, a longtime ally of Assad, after it vetoed a U.N. Security Council resolution that backed an Arab League call for his ouster.

But the Russian mediation failed to slow a rush by countries that denounced the Russian-Chinese veto three days ago to corner Syria diplomatically and cripple Assad with sanctions in hopes of removing him and encouraging reforms to avert chaos in a region straddling major fault lines of Middle East conflict.

Opposition activists said government forces renewed shelling of the central city of Homs on Tuesday just before Lavrov's arrival, killing some 19 people in an onslaught that they say has claimed over 300 lives in the last five days.

There were also reports from residents of shelling and fighting on Tuesday between government and rebel forces in Hama, another urban stronghold of anti-Assad sentiment.

Syria says Homs - the heart of 11 months of protest against Assad's rule, parts of which are held by insurgents including army defectors - is the site of a running battle with terrorists directed and funded from abroad.

Its references to foreign interference are widely read to include Gulf Arab states, which followed the lead of Washington and European Union countries on Tuesday in reducing their diplomatic presence in Damascus.

Russian media quoted Lavrov as saying Assad had assured him he wanted an end to violence by both sides and an expanded Arab League monitoring mission, and that a referendum would be held on a new draft constitution, followed by free elections.

President Assad informed (me) that he will meet in the coming days with the commission that prepared a draft of the new constitution, state-run Russian news agency Itar-Tass reported. The work is finished, and now a date will be announced for a referendum on this important document for Syria.

FREE ELECTION

In remarks carried by state-run Rossiya-24 television, Lavrov said: On the basis of this new Basic Law (constitution), general elections will be organised and conducted in which many parties will participate. The elections will be held on the basis of a new constitution in which there are no privileges or advantages for (Assad's) Baath Party.

Syrian state television said the commission dealing with a new constitution had completed its work on Tuesday.

The state news agency SANA quoted Assad as saying Syria would cooperate with any effort to resolve its crisis that promotes stability in the country.

Syria from the beginning has welcomed any efforts that back the Syrian solution to the crisis, SANA quoted Assad as saying while meeting Lavrov.

Lavrov told Interfax that Assad assured us he was 'completely committed to the task of stopping violence regardless of where it may come from,' and was ready for dialogue with all political groups in Syria.

Opposition activists have dismissed similar pledges of reform made by Assad in the past because he continued trying to crush protests with tanks and branded his foes as terrorists.

Lavrov, whose government wields unique leverage as a major arms supplier with long-standing political ties to Damascus, also told Assad it was in Russia's interest for Arab peoples to live in peace and agreement.

Lavrov further affirmed Russia's readiness to help foster the swiftest exit from the crisis on the basis of positions set out in the Arab League initiative, according to Interfax.

Russia has supported an Arab League peace proposal for Syria floated last November envisaging a withdrawal of troops from cities and towns, release of prisoners, and reforms. But there was no indication from Lavrov's quoted remarks that Russia was now backing the League's explicit call on Assad to step down.

Russia's foreign ministry said Lavrov and Foreign Intelligence Service chief Mikhail Fradkov had gone to Damascus because Moscow wanted to see the swiftest stabilisation of the situation in Syria on the basis of the swiftest implementation of democratic reforms whose time has come.

Syrian state television showed hundreds of people gathering on a main Damascus highway to welcome Lavrov. They were waving Syrian, Russian and Hezbollah flags and held up two Russian flags made out of hundreds of red, white and blue balloons.

BOMBARDMENT OF HOMS RESUMES

Opposition activists said the fresh assault on Homs came after 95 people were killed on Monday in the city of one million, Syria's third biggest. More than 200 were reported killed there by sustaining shelling on Friday night.

The bombardment is again concentrating on Baba Amro (district of Homs). A doctor tried to get in there this morning but I heard he was wounded, Mohammad al-Hassan, an activist in Homs, told Reuters by satellite phone. There is no electricity and all communication with the neighbourhood has been cut.

A further 19 people were killed and at least 40 wounded in Tuesday's barrage, activists said. Some reported fighting between army defectors and government forces trying move into areas the rebels hold in Homs.

Activists and residents of areas near the border town of Zabadani, where army defectors have a toehold after Assad's troops withdrew under a ceasefire, said the government forces renewed shelling on Tuesday morning.

At least nine people have been killed by heavy weapons fire into the town since Monday, activists said.

Syria maintains the military is fighting terrorists in Homs bent on dividing and sabotaging the country. State media said tens of terrorists and six members of the security forces were killed in clashes there on Monday.

Assad has said parliamentary elections will be held when the constitution is approved, but has also pledged to eradicate terrorists he associates with the violence.

Syria's opposition, which rejected a Russian invitation for talks with Syrian officials in Moscow, says Assad's promises of reforms have been discredited by persistent armed attacks on protests, in which the U.N. says 5,000 people have been killed.

HYSTERIA

Moscow and Beijing were the only members of the 15-member U.N. Security Council to vote against the resolution backing an Arab League call for Assad to yield power and start a political transition. The double veto prompted unusually undiplomatic Western criticism, which Lavrov said verged on hysteria.

The Gulf Cooperation Council (GCC) said its members were recalling their ambassadors from Damascus and expelling Syrian envoys from their own capitals, in response to surging violence.

It is necessary for the Arab states... to take every decisive measure faced with this dangerous escalation against the Syrian people, the Saudi-led bloc said in a statement, adding: Nearly a year into the crisis, there is no glint of hope in a solution.

Saudi Arabia, the world's top oil exporter, was the first country to pull out of an Arab League monitoring in Syria, followed by the other five GCC members. The collapse of that mission set the stage for the U.N. Security Council showdown.

European Union states followed up their denunciation of the veto by preparing a new round of sanctions on Syria, EU diplomats said on Tuesday, with the focus on central bank assets and trade in precious metals, gold and diamonds.

Turkish Prime Minister Tayyip Erdogan, an ex-ally who has turned against Assad, described the U.N. vetoes as a fiasco for the civilised world and said Ankara was preparing a new initiative with those who oppose the Syrian government.

RUSSIAN CLOUT

Russia, keen to retain a Middle East foothold highlighted by naval facilities in Syria, may be torn between trying use its rare clout to shore up Assad and seeking his exit.

One analyst said before Lavrov began his talks with Assad that Russia may try to buy time by counselling the government to make some concessions and reduce the bloodshed.

I think that now, after Russia imposed a veto, Lavrov (is) travelling to tell Assad that we did everything possible, said Fyodor Lukyanov, editor of the journal Russia in Global Affairs.

Now the main task for Lavrov is to tell Assad that if there is no visible change in Syria, then regardless of the Russian position he should be bracing for external military measures.

Russia has argued that Saturday's draft U.N. resolution was one-sided and would have amounted to taking the side of Assad's opponents in a civil war. China's veto of the measure followed Russia's lead, analysts and diplomats said.

Catherine al-Talli, a senior member of the opposition Syrian National Council, said the military assault on Homs appeared to be designed to show Moscow that Assad was in control and could serve until his term expires in 2014.

Assad needs to look strong in front of the Russians. He has not managed to control Homs since the eruption of the uprising and now that he has seen that he faces no real threat from the international community, it appears that he wants to finish off the city, Talli said.

The United States shut its embassy and said all staff had left Syria due to worsening security in the country, which has also been hit by suicide bombings in Damascus.

France, Italy, Britain, Belgium, the Netherlands and Spain recalled their ambassadors from Syria. Japan was considering reducing the number of its diplomatic staff in Damascus.

(Additional reporting by Joseph Logan in Beirut, Mitra Amiri in Tehran, Gleb Bryanski and Steve Gutterman in Moscow, Fiona Ortiz in Madrid and Jonathon Burch in Ankara; Writing by Dominic Evans; Editing by Mark Heinrich)