Indonesia expelled an American expert on Southeast Asian terrorist networks for one year, an official said Friday, saying her activities could cause public disorder.

It is the second time that Sidney Jones, the project director for the International Crisis Group in Jakarta, has been barred from the country in as many years.

"I don't understand," said Jones, who was turned back at Indonesia's airport Thursday on return from a short trip to Taiwan. She is now in Singapore.

"If there was a problem, you would have thought they would have called me in or raised the question while I was in Jakarta, giving me some ability to respond," she said.

The Brussels-based International Crisis Group opened an office in Indonesia in 2000 and has issued detailed and well-researched reports on separatist conflicts in Indonesia and the activities of the Al Qaeda-linked Jemaah Islamiyah.

Jemaah Islamiyah has been blamed for at least four deadly bombings in Indonesia since 2002, including last month's triple suicide attacks on the resort island of Bali that killed 20 people.

Immigration department spokesman Supriatna Anwar said Jones would be barred from the country for one year.

"According to the law, anyone who enters Indonesia should be useful and not cause public disorder," he said without elaborating. "Maybe the government feels that at the moment she is not fulfilling those conditions."

Jones, of Albany, N.Y., is frequently interviewed by local and international media, but it is not clear what she may have said in recent weeks to anger the government. Since the Oct. 1 attacks, she has been largely complimentary about Jakarta's successes in cracking down on terrorists.

Jones was expelled from Indonesia in 2004 under the administration of President Megawati Sukarnoputri for allegedly publishing false reports damaging to the country's image.

President Susilo Bambang Yudhoyono's government allowed her to return in July, providing her with residence and work visas.

Jones arrived in Jakarta after attending a Time magazine awards ceremony honoring her think tank's work, and said she was told that an Oct. 7 letter banned her from entry.

The International Crisis Group describes itself an independent, nonprofit organization working to prevent and resolve conflicts. It is funded by foreign governments and private foundations.

The group said it was "shocked and mystified" by the decision to expel Jones.