Washington: The United States said that new terrorist attacks in Indonesia may be imminent and expanded existing warnings to US citizens to include tourist resorts as potential targets.

The warning from the US Embassy in Jakarta on October 21 – the third terror alert in four days for Indonesia – said Americans should be "particularly vigilant in the immediate future" but offered no details about the nature of the threat.

It also reminds US citizens of the continued potential for attacks outside Jakarta and tourist locations on the resort island of Bali, the site of a deadly bombing on Oct 12.

Britain also warned its nationals on October 21 that it had new intelligence of possible attacks in Indonesia. "Further attacks can, sadly, not be ruled out," Foreign Secretary Jack Straw told Parliament.

The US Embassy in Jakarta said it wished to "remind American citizens of the continuing security threat in Indonesia and to urge Americans to continue to exercise maximum caution and be particularly vigilant in the immediate future", the Embassy said.

"Americans should avoid large gatherings and locations known to cater to a foreign clientele, including but not limited to resorts, tourist sights, night clubs, bars, restaurants and places of worship," it said in a notice to US citizens in Indonesia.

The October 21 warning said that threat of attacks also remained in Yogyakarta, in Central Java and other areas in the vicinity.