Syrian President Bashar al-Assad's forces, trying to hammer the city of Homs into submission, on Wednesday killed 19 more people including two Western journalists in an onslaught that has caused an international outcry for intervention to end the bloodshed.

Hundreds of people have been killed in daily bombardments of Homs by Assad's besieging forces using artillery, rockets and Soviet-built T-72 tanks, stoking fears of Assad subjecting the city to the same devastation as his late father inflicted on the rebellious town of Hama 30 years ago, killing at least 10,000.

With diplomacy to halt Syria's bloodshed at a standstill and Assad's forces intensifying offensives to wipe out rebels, the United States appeared to open the door to eventually arming the Syrian opposition, saying that if a political solution to the crisis was impossible it might have to consider other options.

The Homs district of Baba Amro where the 19 deaths were reported has been under bombardment since February 3, taking the conflict to a new dimension which is bound to dominate Friends of Syria talks in Tunis on Friday where U.S. Secretary of State Hillary Clinton meets officials from 70 countries and groups.

In a further sign of worsening carnage in Syria, activists said that troops and militia loyal to Assad captured and shot dead 27 young men on Tuesday in northern villages in the thick of an 11-month-old uprising against his autocratic rule.

Russia, one of Assad's few remaining allies and seen as retaining some leverage over him, said on Wednesday it was seeking safe passage of aid convoys to Syrian civilians trapped in the spreading violence.

Foreign Ministry spokesman Alexander Lukashevich said Russia, which is a weapons supplier to Syria, has asked the U.N. secretary-general to send a representative to liaise with all sides in Syria for the safe transit of humanitarian convoys.

Our initiative is aimed at providing safety of humanitarian cargo deliveries, we are actively working with Syria and (countries) around it, Lukashevich told reporters.

We are working in this area with the Syrian leadership and representatives of the opposition, with the International Red Cross, he said.

The Red Cross has called for daily ceasefires to allow in urgently needed aid in cities like Homs where residents are near starvation, surviving on collected rainwater, watching the wounded dying and too scared to leave their homes and shelters.

France urged Syria on Wednesday to halt attacks on Homs and allow safe access for aid workers to tend to the wounded.

The opposition Syrian National Council (SNC) said on Wednesday it was coming to the view that military intervention was the only solution to the crisis.

We are really close to seeing this military intervention as the only solution. There are two evils, military intervention or protracted civil war, Basma Kodmani, a senior SNC official, told a news conference in Paris.

ROCKETS KILL TWO WESTERN JOURNALISTS

The two Western journalists were killed when rockets struck and demolished the house they were staying in, activists and witnesses in Homs told Reuters by telephone. They were named as Marie Colvin, an American working for Britain's Sunday Times newspaper, and French photographer Remi Ochlik.

Violence raged unabated. Several YouTube videos taken by local activists in the northern Idlib area, which could not be independently confirmed, showed bodies of young men with bullet wounds and hands tied lying dead in streets.

The men, all civilians, were mostly shot in the head or chest on Tuesday in their homes or in streets in the villages of Idita, Iblin and Balshon in Idlib province near the border with Turkey, the Syrian Network for Human Rights said.

Military forces chased civilians in these villages, arrested them and killed them without hesitation. They concentrated on male youths and whoever did not manage to escape was to be killed, the organisation said in a statement.

Responsibility for this massacre lies with the general commander of the military and armed forces, Bashar al-Assad, the statement said, adding that only one youth survived the shootings.

One video shows the body of three youths, one visibly shot in the chest, on the floor of a house in Balshon.

This is martyr Hassan Abdel Qadi al-Saeed, his brother Hussein and (their relative) Bashir Mohammad al-Saeed. They were liquidated by Assad's forces in the February 21 massacre, a voice of a man showing the bodies says, with the sound of women wailing in the background.

U.S. SHIFT

In Washington, the White House and the U.S. State Department appeared to be shifting away from an emphasis on policy of not arming Syria's opposition and saying little about alternatives.

We still believe that a political solution is what's needed in Syria, White House spokesman Jay Carney said on Tuesday.

We don't want to take actions that would contribute to the further militarisation of Syria, because that could take the country down a dangerous path. But we don't rule out additional measures.

Asked if the United States was shifting its stance on arming Syrian insurgents, State Department spokeswoman Victoria Nuland said Washington did not want to see the violence increase and was concentrating on political efforts to halt the bloodshed.

That said ... if we can't get Assad to yield to the pressure that we are all bringing to bear, we may have to consider additional measures, she said, declining to elaborate.

The first Friends of Syria meeting will coordinate the international community's next steps in response to the nearly year-long uprising against Assad.

The United States and its allies hope the Tunis conference will allow them to begin drawing up a plan for Syria after Russia and China vetoed a Western-backed Arab League peace plan at the U.N. Security Council.

With both Russia and Iran backing Assad's government, political analysts say tacit U.S. support for arming rebel fighters could be risky given Syria's complex ethnic and religious make-up and strategically important position.

ARMY PREVENTS AID SUPPLIES

In Syria on Tuesday, activists said Assad's forces killed more than 60 people in attacks on villages and an artillery barrage on Homs.

The sound of bombardment and sniper fire are echoing across the city, Moulham al-Jundi, a member of the Syrian National Council, told Reuters from Homs.

The army prevents first aid or medical supplies from going in and electricity is cut off 15 hours a day. There has been no mobile phone service for three weeks, said Jundi, who lives in exile in Saudi Arabia and was smuggled into Homs.

Civilians need safe zones and a way has to be found to ensure that medicine and basic supplies reach Homs. There are no hospitals, no schools, no work, no government departments open and most shops are shut.

A delegation from the Syrian National Council, the main Syrian opposition grouping, is due to meet Red Cross officials in Geneva on Wednesday.

Activists' accounts of the violence could not be independently verified. The government bars most foreign journalists from Syria.

Official media said government forces were targeting armed terrorist groups who have been terrifying citizens and attacking security forces and robbing public and private property.

(Writing by Angus Macswan and Mark Heinrich; Editing by Peter Millership)