Jakarta – Indonesian police are hunting down a group of suspected terrorists who are prepared at "any time" to use car bombs and suicide attacks, the police chief warned yesterday.

Meanwhile, police arrested three more suspected Muslim militants in the central Javanese town of Solo, bringing to 18 the number rounded up in the past month in Indonesia. Officers seized a small amount of ammunition, two boxes of TNT and sulphur from the men, said police Lt-General Erwin Mapasseng. He gave no other details.

Police General Da'i Bachtiar said officers had learnt about the threat from the interrogation of suspects being questioned over last month's bombing of the JW Marriott Hotel in Jakarta that killed 12 people. "There are still some terror suspects who are in possession of explosives and they are prepared at any time to use them in car bombs or in vests worn around their bodies," he said. "We are looking for them." Gen Bachtiar was speaking at Jakarta's main mosque after meeting Muslim leaders, some of whom have complained that police were arresting Islamic activists arbitrarily and failing to inform their families.

Later yesterday, more than 50 Muslim activists protested outside the national police headquarters, calling on police to release 15 terror suspects arrested last month. The demonstrators said the suspects, many of whom were active in religious groups in Java, were innocent.

Police have arrested nearly 50 suspects in last year's twin nightclub bombings on Bali island that killed 202 people and the Marriott Hotel blast.

The larger Bali blast came from a car bomb, while a smaller device at a second club was detonated by a suspected suicide bomber. The Marriott blast originated from a car bomb that exploded outside the hotel's lobby.

The attacks have been blamed on the Jemaah Islamiah, an Al-Qaeda-linked militant group. Several key suspects in both strikes are believed to be at large. Security at offices, hotels and bars in Jakarta have been stepped up sharply since the Marriott attack.