The U.S. State Department on Thursday warned Americans not to travel to Pakistan and ordered nonessential government personnel to leave the U.S. Consulate in Lahore because of a specific threat to that diplomatic mission.

In a travel warning, the State Department said the presence of several foreign and indigenous terrorist groups posed a potential danger to U.S. citizens throughout Pakistan.

The personnel drawdown at the Lahore consulate was a precautionary measure and wasn't related to the recent closures of numerous U.S. diplomatic missions in the Muslim world, two U.S. officials said. The consulate in Lahore was scheduled to be closed for the Eid holiday from Thursday through Sunday and no reopening had been scheduled, one of the officials said.

The officials were not authorized to discuss the order by name and requested anonymity.

A spokeswoman at the U.S. Embassy in Islamabad, Meghan Gregonis, said, ``We received information regarding a threat to the consulate. As a precautionary measure, we are undertaking a drawdown of all except emergency personnel.''

The U.S. is evacuating staff to Islamabad, said Gregonis. Emergency personnel will stay in Lahore and the embassy officials do not know when the consulate in Lahore will reopen. The U.S. will continue to evaluate the threat reporting.

Gregonis said the threat was specific to Lahore.

Earlier this week, 19 U.S. diplomatic outposts in 16 countries in the Middle East and Africa were closed to the public through Saturday and nonessential personnel were evacuated from the U.S. Embassy in Yemen after U.S. intelligence officials said they had intercepted a recent message from al-Qaida's top leader about plans for a major terror attack.

None of the consulates in Pakistan or the U.S. Embassy in Islamabad were affected by the earlier closures. (AP)