Police in Indonesia have seized a huge cache of explosives, weapons and ammunition. The authorities say that a group of Islamic militants were planning another attack on the scale of the car bombing in Bali last October, in which more than 200 people died. Despite this latest success, analysts are warning that the militants are still capable of striking again.

Most of the weapons and explosives were found in a house in the central Javanese city of Semarang. The police found nearly 900 kilograms of Potassium Chlorate, the chemical fertilizer that formed the basis of the Bali bomb.

Along with the fertilizer, they say they found more than 160 kilograms of TNT, detonators, guns and 22,000 rounds of ammunition. Four people were arrested in Semarang. The police say they are all members of Jemaah Islamiya, or JI, a regional terrorist group which is dedicated to using violent means to establish an Islamic superstate across much of South East Asia.

Police also say they have arrested two senior JI members in a house in Jakarta. The head of the police in Jakarta, General Makbul Padmanegara, told journalists Friday that they had found a list of targets at the house, but declined to give further details.

They also found a third man in the house, but say that, despite being handcuffed, the man managed to seize a gun, load it and run into a bathroom where he shot himself fatally in the chest.

Although many key members of Jemaah Islamiyah are now behind bars, Sidney Jones of the International Crisis Group, a Brussels-based think-tank, warns that the terror group still poses a serious threat. She says loose affiliations among militant groups make it difficult to make a clean sweep of the groups' members.

"To me when you combine that fact, with the fact that several top leaders are still at large, means that the capacity for serious damage is still here," said Ms. Jones.

JI has been accused of a number of terrorist attacks in Asia in addition to the Bali bombing. These include a series of explosions outside churches across Indonesia three years ago, which killed 19 people, and a number of deadly blasts in the Philippines.

Alleged members of JI have also been arrested in the Philippines, Singapore and Malaysia, where they are accused of planning or carrying out terrorist acts.