The U.S. Embassy extended a terrorist alert in Thailand Monday that has brought in heavily armed Thai troops to guard embassy buildings.

"The original 48-hour advisory is being revised to show the threat of terrorist action extends over several days," said U.S. Embassy spokesman Neil Klopfenstein.The alert, sparked by information received Saturday about "a credible threat" of terrorist action in Thailand was now due to expire Jan. 28.

Troops and police have been guarding the U.S., British, Australian and Israeli embassies as well as Don Muang International Airport.