The United States has withdrawn its ambassador to Syria over concerns for his personal safety.

U.S. officials said Monday that Ambassador Robert Ford left Syria during the past few days.

Ford has angered Syrian authorities by speaking out against a government crackdown on protesters calling for President Bashar al-Assad to step down.

In July, the government issued an order restricting the movements of foreign ambassadors after Ford and the French ambassador to Syria visited the flashpoint city of Hama to show solidarity with residents there.

Last month, an angry mob confronted Ford as he prepared to meet a leading opposition figure in Damascus.

The United Nations says Mr. Assad's ongoing crackdown on dissent has killed more than 3,000 people. The government says terrorist gangs have killed hundreds of security personnel in the unrest.