Indonesian police are trying to establish whether one of two men arrested during a raid in central Java is terror suspect Noordin Mohamed Top.
Indonesian police have exchanged gunfire with the occupants of a house in Java, believed to include one of South-East Asia's most wanted men.
The arrests came after police surrounded a house in the region and exchanged fire with suspected militants on Friday afternoon.
Police said the anti-terror operation in the Temanggung district followed the arrest on Friday of several suspected militants loyal to Noordin Mohamed Top.
Noordin, a Malaysian citizen, is one of the most wanted men in South-East Asia.
Mr Noordin, a Malaysian citizen, is suspected of involvement in last month's bombings of two Jakarta hotels.
He is suspected of involvement in last month's bombings of two hotels in Jakarta and the 2002 Bali blasts.
Later, police said they had killed two suspected militants near the capital.
He is also thought to have been behind bomb attacks on the Jakarta Marriott in 2003 and the Australian embassy in 2004, and also on a series of restaurants in Bali in 2005 in which more than 20 people were killed.
Three others were arrested and up to 500kg of explosives were seized in the raid on a house in Bekasi early on Saturday, police said.
Raid 'ongoing'
Gen Bambang Hendarso Danuri told the Associated Press the explosives were intended for "a specific target", but gave no details.
Noordin, a Malaysian national, was thought to be a key recruiter and financier for a regional Islamist militant group, Jemaah Islamiah, but has now formed his own militant group.
A lull in militant attacks since 2005 came to an end in July with suicide attacks on two hotels in Jakarta, raising concerns that Noordin was becoming active again.
Friday's shoot-out took place in Temanggung district in central Java and involved an elite anti-terror unit, police said.
Reports said the raid was still going on after several hours of sporadic gunfire.
Anti-terrorism officials said the police had arrested two men, one of whom they believed might be Noordin. They were in the process of confirming his identity.
Indonesian police have in the past mistakenly thought they had arrested him.
Correspondents say the search for Noordin has focused on central Java because he is believed to have a network of sympathisers there.
He is the Indonesian police's main target and there is a $100,000 (£59,000) reward for information leading to his capture.
