Beirut: The American Embassy in Syria says US Ambassador Robert Ford has been "temporarily" called back to Washington.
But Haynes Mahoney, the Deputy Chief of Mission at the US Embassy, would not say whether the move was connected to security concerns linked to the country's uprising.
Mahoney emphasised on Monday that Washington had not formally recalled Ford.
Ford's trip comes at a time of great turmoil in Syria, which has seen months of mass anti-government protests calling for the ouster of President Bashar Assad.
Last month, Ford and several colleagues from the embassy were pelted with tomatoes and eggs as they visited an opposition figure.
US officials said the assault was part of a campaign to intimidate diplomats investigating Assad's repression of pro-reform demonstrators.