ISLAMABAD, Pakistan -- The U.S. Consulate in the Pakistani city of Lahore was shut on Friday with only emergency staff remaining on duty following "specific threats," officials said.
The State Department also advised U.S. citizens against traveling to Pakistan.
Most American diplomats and staff based in Pakistan's second-largest city were ordered to stay home "due to specific threats," according to the State Department.
"As a precautionary measure, we are undertaking a drawdown of all except emergency personnel," U.S. Embassy spokeswoman Megan Gregonis said.
She said it was unclear when the diplomatic post in Lahore would reopen.
"We will continue evaluating the threat reporting," Gregonis added.
The threats that prompted the consulate's evacuation is different from the one that temporarily shuttered 19 U.S. diplomatic posts in the last week, a senior State Department official said.
None of the consulates in Pakistan or the U.S. Embassy in Islamabad were affected by the earlier closures, which was prompted when intelligence agencies intercepted an electronic communication between two of al Qaeda's top leaders in which they agreed they "wanted to do something big" this past Sunday, according to sources.
The warning in Lahore, near Pakistan's border with India, comes two days after Washington evacuated some diplomats from Yemen and told its nationals to leave that country immediately.
Pakistan had already beefed up security at military buildings, airports, prisons and other sites following other recent threats. United Nations Secretary General Ban Ki-Moon is also due to visit the country next week.
The State Department's new travel alert warns that "terrorist groups continue to seek opportunities to attack locations where U.S. citizens and Westerners are known to congregate or visit."
The country has faced a bloody insurgency by the Pakistani Taliban and their allies in recent years that has killed more than 40,000 civilians and security personnel, and is also believed to be home base for al Qaeda leader Ayman al-Zawahiri.
Meanwhile, gunmen in Quetta attacked a mosque during Eid prayers on Friday, killing nine and injuring 15.
Fakhar ur Rehman, Mujeeb Ahmed and Jason Cumming, NBC News. NBC News' Andrea Mitchell, Catherine Chomiak and Daniel Arkin, The Associated Press and Reuters contributed to this report.