Indonesian police have arrested nine suspected Jemaah Islamiah militants linked to last year's Bali attacks and seized explosives and chemicals capable of making a bomb 10 times bigger than those which hit the island.
Underscoring the threat to the world's most populous Muslim nation, police said they had also foiled plans by Islamic radicals to attack churches and shops in Jakarta.
But they denied rumors swirling around Indonesia that they had also caught Jemaah Islamiah's alleged operations chief, known as Hambali.
Police said one of the arrested militants committed suicide by shooting himself with an M-16 rifle shortly after being arrested yesterday near President Megawati Sukarnoputri's main private home.
He was handcuffed at the time but managed to grab the weapon, put in a magazine and turn it on himself, police said.
The al-Qaeda-linked Jemaah Islamiah has been blamed for the October Bali bomb attacks that killed 202 people, mainly foreign tourists, and other bombings in Southeast Asia.
Police have already arrested 30 militants over Bali. The latest took place over the past week in several locations.
Officers seized a pair of M-16s, 22,000 rounds of ammunition, 160kg of TNT, 900kg of potassium chlorate, detonators and books on bombmaking in raids in Jakarta and Semarang, capital of Central Java province. Most of the explosives were found in Semarang.
"This is not a joke. It is clear that this was preparation for a bomb," Central Java police chief Didi Widayadi said.
Asked if the power of the explosives was 10 times greater than the force of the blasts in Bali, Widayadi said. "More than that."
He said four men caught in Semarang were "very militant and ready to die."
One of the militants arrested in the Jakarta area was Pranata Yuda, also called Mustofa, 42, Jemaah Islamiah's former chief for a region that incorporates parts of eastern Indonesia, Malaysia and the southern Philippines, police said.
"He [Mustofa] had prepared the next targets following the Bali bombings," Jakarta police chief Makbul Padmanegara told a news conference, adding sketches of those plans had been seized.
Makbul said another suspect caught in Jakarta, Ichwanudin also known as Asim, 28, shot himself in the chest yesterday while in detention. It was unclear if this was at police headquarters.
"With much skill, he grabbed the M-16 and instantly loaded it with a magazine, then ran to the toilet and killed himself," Makbul said, adding the man was Jemaah Islamiah's Jakarta chief.
Most of the suspects had links to Afghanistan and Muslim rebels in the southern Philippines, police said.
Makbul said police had found a Jemaah Islamiah basecamp near Semarang, although he gave no details. Other arrests were made in Central Java.
Rumors have swept Jakarta for days about the capture of the alleged Jemaah Islamiah operations chief Hambali, an Indonesian Muslim preacher in his late 30s who is the most wanted man in South-east Asia and said to be the top regional representative for the al-Qaeda network of Osama bin Laden.
Yesterday, one leading newspaper quoted unidentified sources as saying Hambali had been shot on the outskirts of Jakarta and was being treated in a police hospital.
His capture would be a major coup for the Jakarta government.