Indonesian police have uncovered a cache of weapons and explosives at the house of a man accused of hiding one of the suspects in the Bali bombing.

When they raided a house in East Java, the police found 13 handguns, almost 2,500 rounds of ammunition and 150 kilograms of potassium chlorate, similar to that used in last year's Bali car bombing.

The house belongs to 34-year-old Azhari Dipo Utomo. Police have arrested Mr. Utomo, who works as a math teacher in an Islamic school, and have accused him of hiding Ali Imron, one of the alleged Bali bombers.

Police have said Mr. Imron parked a minivan carrying a huge bomb outside a crowded nightclub on the island of Bali on October 12. More than 190 people died in the blast, most of them young Western tourists.

Mr. Imron also is suspected of buying much of the explosives, including almost a ton of potassium chlorate. Some of it was used in Bali, but large quantities are missing.

The police did not say if the potassium chlorate found in Mr. Utomo's house is part of the same lot.

The police have arrested 17 suspects in the bombing. They suspect the bombers could be part of a larger group of Islamic extremists who plotted to attack domestic and international targets in Indonesia and other parts of South East Asia.

Washington thinks that a regional organization called Jemaah Islamiyah has been behind much of the violence in the region, and has declared JI, as it is known, a terrorist organization. Many of the Bali suspects have been linked to JI. The police say they found a book about JI in Mr. Utomo's house.