An Indonesian Muslim cleric believed by the U.S. and several Southeast Asian governments to be linked to regional terrorism has been arrested. Abu Bakar Bashir was put under guard Saturday in the hospital which admitted him after he became ill the day before.

Authorities say Abu Bakar Bashir is now held under guard at a hospital in Solo, his hometown in central Java. The 64-year-old Muslim cleric was admitted to the hospital late Friday, complaining of respiratory problems.

Police had issued a summons for Mr. Bashir to show up in Jakarta for questioning on Saturday. The summons relates to a series of bombings of churches across Indonesia on Christmas Eve in 2000. Nineteen people died in those bombings and dozens were injured. Mr. Bashir failed to answer the summons, going to the hospital instead.

Although he is now under arrest, Mr. Bashir has not yet been questioned by the police. The U.S. and several of Indonesia's neighbors have said Mr. Bashir is the leader of Jemaah Islamiah, a militant group believed to have links to al-Qaida. JI, as the group is known, wants to create an Islamic state across Southeast Asia.

So far, the Indonesian authorities have not linked Mr. Bashir to last week's bombing in Bali, which claimed the lives of at least 180 people and injured hundreds more. Many of the dead are foreign tourists, and the majority of them appear to be Australians.

The Australian government on Saturday issued a warning that Westerners in Indonesia face possible new terrorist attacks, and recommended that Australian nationals leave the country, the second such warning Australia has issued in three days. Mr. Bashir has consistently denied any connection to terrorism, although he is an outspoken admirer of al-Qaida leader Osama bin Laden. He has also denied playing any part in the Bali bombing.

He has said that he believes that the U.S. engineered the Bali bombing in order to justify a crackdown against Muslim groups.

The arrest of Mr. Bashir comes a day after the Indonesian government passed two anti-terror decrees. The first allows authorities to detain alleged terrorists based on intelligence information, initially for three days. But the detention may be extended up to six months. Those convicted of committing terrorist acts face the death penalty.

The second decree allows the new anti-terror legislation to be used retroactively, so that it can be applied to the Bali bombing. So far, the Indonesian authorities have accused no individual or group in that bombing.

Those new laws come into affect after months of pressure on Indonesian President Megawati Sukarnoputri by regional governments and the United States to do more to counter terrorism. A senior U.S. official in Jakarta said Friday that he believes Indonesia is at a crossroads in its efforts to combat terror, and that how it acts in the coming days will have historic implications.