Authorities are making progress in the investigation of a bombing in Bali that killed nearly 200 people, with investigators now concluding that three, not two, explosives were used in the attack, police said Sunday.

Meanwhile, authorities considered how to interrogate the ailing spiritual leader of a group suspected of carrying out the Oct. 12 nightclub attack as about 100 Islamic students protested outside a hospital to prevent police from removing him.

"We want to make sure that police will not take Abu Bakar Bashir from hospital until he recovers," said Mudzakir, one of the students gathered in front of the Muhammadiyah Hospital in the town of Solo where Bashir is being treated for breathing problems.

Armed policemen monitored the protest but did not intervene.

Bashir, a cleric who runs an Islamic school, was arrested Saturday on suspicion of involvement in a series of church bombings two years ago. He is the spiritual leader of Jemaah Islamiyah, a group widely believed to have carried out last week's bombings.

Bashir denies any role in either incident.

In Bali, Gen. Edward Aritonang, a national police spokesman, said authorities now believe that three explosions destroyed Paddy's pub and Sari's nightclub on the island of Bali.

Previously, police assumed an initial, smaller blast damaged Paddy's seconds before a much more powerful explosion at nearby Sari's, causing most of the casualties.

It was not immediately known how they arrived at that conclusion.

Aritonang said authorities believed there was no link between a grenade blast near the office of the honorary U.S. consul around the time of the Bali nightclub attack. There were no casualties in the grenade attack.

The investigation -- conducted jointly by more than 100 investigators from Indonesia, Australia, the United States, Britain and other countries -- was proceeding well, Aritonang said.

"There has been some progress now," Aritonang told reporters.

Bashir, 64, is under guard at the main hospital in Solo. A team of police doctors was checking whether the cleric is healthy enough to travel to Jakarta, 250 miles to the west, for questioning.

Bashir's doctors said he was improving and could be released in two or three days.

Police are considering confining the cleric to Solo under police supervision, or taking him to a police hospital in Jakarta and holding him there.

President Megawati Sukarnoputri on Friday signed an emergency decree that allow suspects to be detained for up to six months without charge.

Warning of the threat of new terrorist attacks, Australia urged its citizens to leave Indonesia. The United States advised Americans to put off travel to the country.

On Sunday, as Australia held a day of mourning for more than 100 of its citizens feared dead from the Bali attack.

"I believe -- although I cannot prove -- it is part of a worldwide terrorist operation," Prime Minister John Howard said.

Other countries in Southeast Asia said they would tighten security, but there were signs of fear spreading outward from Indonesia. Australia postponed a film festival and education fair in Malaysia -- which has been cracking down on extremists for more than a year -- because of regional terrorism fears.