The U.S. Embassy in the Sri Lankan capital Colombo was closed Tuesday following an unspecified security threat.
U.S. embassy spokesman in Colombo, Chris Long, says all embassy staffers were sent home following the security threat.
"The American Center and the embassy are both closed for security reasons for an indefinite period," he said.
Mr. Long did not provide details of the threat itself. Reports citing unnamed diplomatic and police sources says the embassy was shut after a letter was received containing white powder - raising fears of an anthrax-type attack.
In 2001, five people in the United States died after contact with the powder that causes the disease anthrax, which had been mailed to a handful of media and government offices. The case has not been solved.
The closure of the embassy in Colombo comes less than a week after the partial closure of the U.S. embassy in the Indian capital New Delhi.
Officials declined to comment on media reports that the closure in New Delhi, which lasted one day, was connected to the al-Qaida terror network.
The threats to the embassies come at a time of heightened security alerts in the United States and other countries following the arrest of more than two dozen al-Qaida suspects in Britain and Pakistan.