France will close its embassy in Damascus after three weeks of bloody shelling by government forces saw rebel fighters forced to withdraw from the city of Homs.
President Nicolas Sarkozy made the announcement at an EU summit where new sanctions against the regime are being discussed.
The French foreign ministry also announced that the two French journalists evacuated from Homs on Thursday will return to France on Friday.
Edith Bouvier, whose leg was broken in the same attack which killed Sunday Times reporter Marie Colvin and French photographer Remi Ochlik.
The Red Cross said that a convoy of seven trucks carrying aid to Baba Amr in Homs had reached the city on Friday and were preparing to distribute help to the 4,000 civilians still stuck in the city.
Elsewhere the UN said it was alarmed at reports of summary executions taking place in Homs and was trying to investigate.
Government forces took control in the city after a sudden ground invasion followed more than three weeks of brutal shelling, which killed hundreds of civilians.
Around 4,000 residents in Baba Amr were left behind in fear of a "massacre", said the Syrian National Council.
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British Prime Minister David Cameron said Assad's move to allow aid would not prevent his eventual "day of reckoning".
Speaking at an EU summit in Brussels, where it is expected that fresh sanctions will be imposed on the regime, Cameron said it was "vitally important" that humanitarian aid reached Homs.
He said: "What we are going to be discussing today though is the situation in Syria which is absolutely appalling and it is vitally important that there is humanitarian access in to Homs and elsewhere so that people can get the help they need.
"But above all, what I think matters, is building the evidence and the picture so we hold this criminal regime to account and make sure that it is held to account for the crimes it is committing against its people and that one day, no matter how long it takes, there will be a day of reckoning for this dreadful regime."