Fighting between rebels and the government forces raged near the Syrian capital Damascus, forcing an inbound commercial jet to turn back while the United Nations said it was withdrawing its staff from the country because of deteriorating security conditions.
Lebanese security officials said Jihad Makdissi, a polished foreign ministry spokesman known for defending the regime of President Bashar Assad in fluent English, flew from Beirut to London. But it was not immediately clear whether he had defected.
The fighting over the past few weeks in and around Damascus has been the most serious in the capital since July, when rebels captured several neighbourhoods before a swift government counteroffensive swept them out.
The spike in violence recently is concentrated in the ring of mostly poor suburbs around Damascus but often bleeds into the capital itself as rebels bring their fight closer to Assad's seat of power.
Assad's forces have so far repelled major rebel advances on the capital, though their hold may be slipping.