The U.S. government has withdrawn its ambassador to Syria Robert Ford because of "credible threats" against his safety, the State Department said in a statement Monday.

"Ambassador Robert Ford was brought back to Washington as a result of credible threats against his personal safety in Syria," State Department spokesman Mark Toner said.

"At this point, we can't say when he will return to Syria," he said, adding "it will depend on our assessment of Syrian regime-led incitement and the security situation on the ground."

Ambassador Ford left Syria Saturday for a "two-week vacation," a second secretary at the U.S. embassy in Syria's capital of Damascus told Xinhua Monday.

On Friday, Ford was hit with eggs and tomatoes while he was visiting the central Midan neighborhood of Damascus.

Ford paid controversial visits to many restive areas in Syria recently in a show of support to anti-government protestors.

Syria has been plagued by unrest since mid-March when protests against President Bashar Assad's government erupted.

More than 3,000 people including army and security members have been killed in the turmoil, according to figures released by the United Nations.