Australia put out an increased warning to its nationals in Indonesia Sunday. The warning included advising citizens to leave parts of the island of Sulawesi, where there are a number of Australian-operated mining projects.

The Australian warning comes on the heels of a similar statement by the United States Embassy in Jakarta. That warning advised U.S. citizens to take extra security precautions because what it described as a convergence of local and international factors had increased the threat to Americans in Indonesia.

"We've sent out another warden message, which is a message to American citizens residing in Indonesia, about the need to be continuously vigilant and careful in their movement in Indonesia, to continue to be aware of their surroundings, to be aware of the continued potential for terrorist attacks against Americans or American interests," said Stanley Harsha, a spokesman for the U.S. Embassy in Jakarta.

Security experts in Jakarta, speaking on condition of anonymity, say intelligence agencies have received specific evidence of an increased threat to Western embassies and diplomats. They declined to say what that evidence was or how it was gathered.

Some embassies have been ratcheting up their security over the past few days, including requesting extra personnel from the Indonesian police, randomly changing work patterns and advising staff to vary their daily routines.

But it appears none have moved to send staff out of Indonesia, which would signal an important escalation of the threat.

Indonesia is home to Jemaah Islamiyah, or JI, an Islamic extremist group with links to Osama bin Laden's al Qaida network. JI was behind the October 2002 bombing on the island of Bali, which killed more than 200 people, and last August's car bombing of the U.S.-run J.W. Marriott Hotel in Jakarta, in which 12 died.