Syrian forces bombarded districts of Homs city on Saturday in a campaign to crush a revolt against President Bashar al-Assad, whose ally Russia said it would not support an Arab peace plan circulating at the United Nations.

Activists said seven people were killed in the latest attacks in a week-long government siege of Homs, which has been at the heart of the uprising which broke out 11 months ago.

Mohammed Hassan, an opposition campaigner in the western city, told Reuters by telephone that a 55-year-old woman was among those killed by shellfire on the Bab Amro district.

The bloodshed followed Friday's violence, when bombings targeting security bases killed at least 28 people in Aleppo and rebel fighters battled troops in a Damascus suburb after dark.

Assad has ignored repeated international appeals, the latest from the European Union, to halt his crackdown.

I condemn in the strongest terms these acts perpetrated by the Syrian regime against its own civilians, EU foreign policy chief Catherine Ashton said.

However, the world is deeply divided over how to end the conflict. A week ago, Russia and China vetoed a draft U.N. Security Council resolution sponsored by Western and Arab states that backed an Arab League call for Assad to step down.

With Syria in worsening turmoil, Saudi Arabia has circulated a new draft for the General Assembly similar to the earlier one.

But Russian Deputy Foreign Minister Gennady Gatilov said on Saturday Moscow could not support a move at the U.N. General Assembly resting on the same unbalanced draft resolution text.

HOMS SUFFERS

The diplomatic dispute brings no relief to Homs, where the government offensive on mostly Sunni Muslim rebel-held areas has killed at least 300 people in the past week, activists say.

Food and medical supplies are running low in blockaded areas and many people are trapped in their houses.

Accounts could not be independently confirmed as Syria restricts access by most foreign journalists.

Youtube footage provided by activists showed a doctor at a field hospital next to the body of the woman. Shrapnel hit her in the head and completely drained her brain matter, he says.

The 46-year-old Assad belongs to the Alawite sect, an offshoot of Shi'ite Islam that has dominated the majority Sunni country since his late father took control in a 1970 coup.

Security forces have also made house-to-house raids in Homs in the last two days. The bodies of three people shot by snipers were pulled from the streets on Saturday, activists said.

YouTube footage from Friday showed two tanks said to be on the edge of Bab Amro, one firing its main gun across a highway.

The indiscriminate shelling is killing mostly civilians, Fawaz Tello, of the opposition Syrian National Council, told Reuters, arguing that Assad wanted to avoid pushing his troops into street fighting and was banking on the bombardment to force rebel fighters to withdraw.

AMBUSH AND ASSASSINATION

In Damascus, gunmen shot dead a senior Syrian military doctor outside his home in northern Damascus on Saturday, the state news agency SANA said.

It blamed an armed terrorist group for killing Brigadier-General Issa al-Khouli, who it described as a doctor and hospital director. He was the most senior official to be reported killed in Damascus.

That killing followed a four-hour clash in the capital on Friday night pitting Free Syrian Army rebels against troops backed by armoured vehicles who had entered al-Qaboun neighbourhood, activists said. ID:nL5E8DACME]

The Syrian Observatory for Human Rights said 10 soldiers were killed in an ambush by army defectors using roadside bombs and hand grenades on Friday in the rebellious Idlib region.

The British-based Observatory also reported three people killed in bombardments of the opposition stronghold of Zabadani.

In Douma, south of Damascus, an officer and eight soldiers defected along with a tank after clashes between army deserters and security forces, it said.

Opposition to Assad has evolved from pro-democracy street protests to armed insurrection over the past 11 months and world powers fear a slide into civil war with knock-on effects for Syria's neighbours - Turkey, Iraq, Jordan, Israel and Lebanon.

REGIONAL RISK

Gulf Arab states, the United States, Europe and Turkey hope diplomacy can force Assad out and have ruled out military action of the kind that helped oust Libya's Muammar Gaddafi last year.

Assad can count on the support of Russia, Syria's main arms supplier and an ally stretching back to the Soviet era, as well as Iran. Moscow, which is keen to counter U.S. influence in the Middle East, insists foreign powers should not interfere.

The U.N. assembly is due to discuss Syria on Monday and vote

later in the week on the draft resolution, which fully supports an Arab League plan floated last month.

The Arab League will meet in Cairo on Sunday to discuss the idea of a joint Arab-U.N. monitoring mission for Syria.

Ayham Kamel, a Eurasia Group analyst, said the Russian and Chinese vetoes showed that change in Syria was not imminent. As rebel forces lacked structure and a unified command, Assad would keep the military edge but find it hard to crush the revolt.

In the next few months, Syria will transition from civil conflict into civil war. Assad's power and control over the country will diminish and civilian casualties on both sides are expected to rise, Kamel said.

Highlighting the danger of the conflict spilling over borders, supporters and opponents of Assad fought in the streets of Lebanon's northern city of Tripoli on Saturday, a security source said. Two people were killed and eight wounded, some of them soldiers who had been deployed to halt the fighting.

(Additional reporting by Patrick Worsnip at the United Nations and Gleb Bryanski in Moscow; Writing by Angus MacSwan in Beirut; Editing by Alistair Lyon)