The Syrian ambassador to Iraq has defected and will seek asylum in Turkey, the most senior diplomat to abandon the regime since the uprising against President Bashar Assad began 16 months ago, a Syrian opposition figure said Wednesday.

The ambassador, Nawaf Fares, is heading to Turkey, said Khaled Khoja, a member of the opposition Syrian National Council. If confirmed, it would be the second major defection to hit the Assad regime in less than a week.

"It's certain. He has defected. He declared his defection," said Khoja, who is based in Istanbul. Asked for details, Khoja said the information came from his own sources on the ground in Syria.

An operator who answered the phone at the Syrian Embassy in Baghdad said there was nobody at the embassy. When asked if the ambassador is currently in Iraq, the operator said he did not know.

White House spokesman Jay Carney said the U.S. had no confirmation of the defection of Syria's ambassador to Iraq as of Wednesday afternoon. But he said other recent high-level defections from the Assad regime were "a welcome development."