The US embassy itself only reopened on Tuesday after closing for several days following an unspecified security threat.

An embassy statement emailed to Americans in Indonesia on Friday said the embassy had learned "there were plans by extremists to conduct bomb attacks targeting the lobbies of hotels frequented by Westerners in Jakarta."

"The attacks were to occur circa noon on an unspecified date," the statement said, adding that there was no additional information on timing or method of attack.

In recent years, Indonesia has suffered sporadic outbreaks of violence between religious groups, as well as bombing attacks blamed on Jemaah Islamiah, a militant Islamic group linked to al-Qaeda.