A man already on Indonesia's most wanted list in connection with a suicide attack five months ago was the bomber who blew himself up in a packed church on Sunday, police said Tuesday.

Ahmad Yosepa Hayat, 31 was sitting among the Bethel Injil Church congregation in central Java's Solo city during a service when he stood up and detonated a bomb strapped to his body, wounding 27 people.

"Fingerprint and DNA tests showed that the bomber is Hayat," national police spokesman Anton Bachrul Alam told a press conference. "He is a member of Jemaah Ansharut Tauhid (JAT) in Cirebon."

JAT was founded by militant spiritual leader Abu Bakar Bashir, who was jailed in June for 15 years for funding a terrorist group planning attacks against Westerners and political leaders.

Hayat, born in Cirebon in western Java, accompanied a suicide bomber to an attack on a police mosque in that city in April which injured 30 people, Alam added.

"He wanted to die as a martyr," he said, adding that Hayat, who had bomb-making expertise, joined the militant group in 2010.

Police have so far questioned 17 witnesses in connection with Sunday's added, Alam said, adding that four suspects linked to Hayat were still at large.

Solo, some 600 kilometres (370 miles) southeast of Jakarta, is Bashir's home town and his Islamic boarding school Ngruki is about 10 kilometres from the bombed church.

The police announcement came after a bomb was thrown at a church but failed to explode in the eastern Indonesian city of Ambon on Monday night and a second device was found near another Christian house of worship.

Ambon is part of the Maluku chain of islands more than 1,700 kilometres (1,060 miles) from Java, which has a long history of major sectarian violence and saw a total of more than 5,000 Christians and Muslims killed between 1999 and 2002.

Two other pipe bombs filled with black powder have been left in the city in recent days, Alam said, one of them found in a bus station and the other exploding but without causing casualties.

Most of Indonesia's 200 million Muslims are moderates, but the country has struggled to deal with numerous attacks by radical extremists, such as the Al-Qaeda-linked Jemaah Islamiyah (JI) which carried out the 2002 Bali bombings that killed 202 people.