600 people have left the besieged ruins of rebel-held central Homs in Syria, escaping more than a year of hunger and deprivation caused by one of the most protracted blockades of Syria's devastating conflict.

The evacuation of civilians and delivery of aid was the first concrete, though modest, result of talks launched two weeks ago in Switzerland to try to end the civil war.

The evacuees, mainly women, children and old men, were brought out by the United Nations and Syrian Red Crescent on the third day of an operation during which the aid convoys came under fire and were briefly trapped themselves in Old Homs.

“The last vehicle has arrived and the total is 611 people,” Homs governor Talal al-Barazi told regional Arab television channel Al Mayadeen at a meeting point for evacuees outside the city, adding that more aid was also sent into the rebel area.

Mr Barazi and Red Crescent officials said they were working to extend the operation beyond today, the final day of a fragile and frequently violated three-day ceasefire in the city.

Amateur video posted on social media showed hundreds of people sheltering behind slow moving UN vehicles as they drove away from the city. At one point a shot rang out but nobody appeared to have been hit.

Some of those who came out were men of fighting age who were not originally eligible to leave, Mr Barazi said, but they had agreed to hand themselves over to police and judicial authorities and could win their freedom through amnesty.

Rights groups have regularly condemned the siege of Homs' rebel districts, where at least 1,200 women, children and elderly people are among some 3,000 surviving on little more than wild herbs and olives.

The peace talks made little visible progress towards reaching a political settlement for the nearly three-year war, which has claimed more than 136,000 lives and displaced millions of people.