BEIRUT  - A bomb went off in front of a mosque and killed 14 people in Homs, Syrian state television said on Friday, with forces loyal to President Bashar al-Assad looking close to wresting the symbolic central city back from rebels.

“Fourteen people were killed and dozens wounded in a terrorist bomb in front of the Bilal al Habshi mosque ... as people left the mosque,” state television said. The mosque is in a government-controlled part of Homs. Syrian authorities generally refer to attacks by rebels as “terrorist”, but there was no way to verify who was responsible for the blast. The Lebanese Al-Mayadeen TV station, which has reporters in Syria, said it was a car bomb.

Hundreds of rebel fighters and civilians remain trapped in the ancient quarter of Homs, surrounded by government forces and pro-Assad militia. A deal agreed at peace talks in Geneva this year allowed some civilians to leave. But further negotiations broke down following heavy fighting this week. A city with a mixed Muslim, Alawite and Christian population, Homs was the scene of early protests against Assad in 2011 that, after he tried to crush them by force, spiralled into an armed insurgency.

Homs has since evolved into a symbol of the destructive nature of Syria’s civil war, with many of its neighbourhoods levelled by army bombardment.

The state news agency SANA quoted a military source on Friday as saying the army had “eliminated” rebels in central Homs and taken control of buildings in Bab Hood and Wadi al-Sayeh neighbourhoods, both contested districts.

The opposition National Coalition, a political body in exile, warned on Thursday of a massacre if Assad’s forces were to push through into the small pocket of rebel-held Homs. More than 150,000 people have been killed in the civil war, a third of them civilians, according to the anti-Assad Syrian Observatory for Human Rights. Millions have fled the country.

The conflict has been broadly stalemated for months, with the government generally dominant in Damascus, the main central cities and western, coastal regions of Syria and the rebels holding wide swathes of the north and east.

Meanwhile, Syrian army forces made advances on Friday around the Old City of Homs, where some 1,200 rebels are dug in and under regime siege, a security source told AFP.

In a government-held district of the city, meanwhile, 14 people were killed when a car bomb exploded outside a mosque after the weekly Muslim prayers, state television reported.

The army, which began a broad offensive against rebel-held parts of the central city on Tuesday, “is progressing daily by capturing buildings and tightening the noose around the terrorist groups,” the security source said.

Syrian authorities refer to all those seeking the ouster of President Bashar al-Assad as “terrorists.”

The source added that regime forces had seized a church in the Old City.

Rami Abdel Rahman, director of the Syrian Observatory for Human Rights, confirmed the army had “advanced,” adding that troops were shelling the Bab Hud and Wadi al-Sayeh districts.

But he said the army had so far only captured buildings rather than whole streets and fighting was continuing.

“There are street battles, but the loyalist forces are not advancing much because the buildings are mined,” said the head of the monitoring group, which collects its information from a network of medics on the ground and opposition activists.

The remaining rebel fighters in Homs “know the area very well and refuse to leave. They want to fight until the end,” he added.

On Thursday, members of the UN Security Council expressed concern over the plight of Syrian civilians caught in the renewed fighting in Homs.

And they called for implementation of a resolution passed in February urging immediate access of humanitarian assistance in all parts of Syria.

In February, a UN-led operation evacuated around half of the 3,000 people trapped under army siege in rebel-held parts of Homs city.

But around 1,200 fighters and some 180 civilians are believed to remain in the Old City and surrounding districts.

On Thursday, UN-Arab League envoy Lakhdar Brahimi urged the Syrian government and opposition to resume discussions about lifting the siege on Homs.

“We urge all the parties to return to the negotiating table and complete the deal which was on the verge of being signed,” he said.

“It is a matter of deep regret that negotiations were brutally stopped and violence is now rife again when a comprehensive agreement seemed close at hand,” Brahimi added.