A top spokesman of Bashar al-Assad's regime has fled Syria, a diplomat in the region said Monday.

Foreign Ministry mouthpiece Jihad al-Makdissi, who is in his 40s, previously worked at the Syrian Embassy in London and returned to Damascus a year ago to defend the government's crackdown on the revolt.

He had little influence in a system largely run by the security apparatus and the military, Reuters reports, but Assad's opponents will see the loss of such a prominent figure, if confirmed, as further evidence of a system crumbling from within.

Rebel forces have made advances in recent weeks, seizing military bases including some close to the capital Damascus. Amid talk that troops had moved chemical weapons, U.S. President Barack Obama again warned Assad against using them.

Makdissi belongs to Syria's Christian minority, which has largely stood behind Assad.

"He defected. All I can say is that he is out of Syria," the diplomatic source, who did not want to be named, told Reuters.

Lebanon's Hezbollah al-Manar Television, citing government sources, said Makdissi was fired for making statements that did not reflect the government's position.

He was rarely seen in the media in recent weeks. His mobile telephone was switched off and there was no immediate comment in Syrian state media. The pan-Arab news channel Al Arabiya said Makdissi had left Beirut and was on his way to London, where he was expected to remain.

"We're aware of reports that he has defected and may be coming to the UK. We're seeking clarification," a Foreign Office spokeswoman said.