Syrian state television said four members of the Syrian Arab Red Crescent were wounded by rebel fighters on Saturday, Feb 8, as the aid workers tried to deliver humanitarian supplies to a besieged, rebel-held district of Homs city, according to Reuters.

It said the Red Crescent members came under fire from "armed terrorist groups", the label authorities give to rebels fighting President Bashar al-Assad. There was no immediate comment from rebel or opposition groups.

The humanitarian convoy had been delayed since Saturday morning by mortar fire in Homs, which the two warring sides blamed each other for, in violation of a three-day ceasefire for civilians to leave central Homs and aid supplies to get in.

The Red Crescent said on its Twitter feed that an aid truck driver had been wounded after shots were fired at the convoy, and that mortar shells also landed close by as the vehicles moved into the Old City.

It posted a picture which appeared to show a bullet hole in the back window of a Red Crescent car.

Syrian television quoted the governor of Homs, Talal al-Barazi, as saying two cars carrying aid supplies had entered the Old City but that rebels had targeted the route with mortar fire, preventing any more vehicles from entering.

The violence threatens to unravel a humanitarian deal for Homs which was the first concrete result of talks launched two weeks ago in Geneva to try to end the country's civil war.

The conflict has killed more than 130,000 people, driven millions from their homes and reduced parts of Syria's cities to rubble.