The United States has warned Americans in Indonesia of a threat by terrorists to attack hotels frequented by Westerners in Jakarta.

The U.S. Embassy in the Indonesian capital issued a security alert Friday, saying it had learned of plans to strike at noon on an unspecified date, although the nature of the attack was not known.

The warning contained no more details. It follows the shutdown of U.S. diplomatic facilities for four days last week after receipt of an unspecified threat.

Militant members of the Jemaah Islamiyah terror group are active in the region. They have been blamed for the Bali nightclub bombings and other deadly attacks on Jakarta's Marriott hotel and the Australian Embassy in the past three years.

Some information for this report provided by AP and AFP.