Indonesian police have confirmed their arrest of four Muslim militants, including the bombmaker, for the suicide blast outside the Australian embassy in Jakarta that killed 11 people in September.

Among the four arrested during a series of raids on November 5 in the West Java town of Bogor was a man called Sogir. He is an associate of fugitive Malaysian explosives expert Azahari Husin, said national police chief Da'i Bachtiar.

Sogir, also known as Ansori, played a "significantly important" role in the September 9 attack due to his bomb-making skills, Bachtiar told a press conference.

"Sogir alias Ansori ... turns out to have played a significant role because [he] is capable of assembling bombs. The bombs which were assembled by Sogir had been tried out or detonated in front of the Australian embassy," Bachtiar said.

Three other men captured during the raids were Rois, who is also known as Iwan Darmawan, Hasan and Apuy, Bachtiar said.

At the press conference, police displayed various battery-powered explosive devices containing TNT and ammunition for handguns which Bachtiar said were seized from the four during the raids.

All four could be charged under anti-terror laws which carry a maximum sentence of death. More than 20 people have so far been detained for the embassy blast.

Rois had been in charge of recruiting Heri Golun, the suicide bomber who died in the explosion in Central Jakarta, the police chief said. Rois also helped assemble the explosives used in the attack and had been tasked to find safe houses for Azahari and his Malaysian compatriot Noordin Mohammad Top.

Azahari and Noordin are believed to have masterminded the embassy attack as well as having played key roles in the October 2002 Bali bombings which killed 202 people and last year's Jakarta Marriott hotel attack in which 12 died.

The Al-Qaeda-linked Jemaah Islamiyah regional terrorist group is blamed for the embassy attack, the Bali and Marriott strikes and a string of other recent bloody attacks in Indonesia.

Australia, which lost 88 people in the Bali blasts, hailed the arrest of the latest suspects. "We welcome the real determination the Indonesians are showing to find the people responsible," said Foreign Minister Alexander Downer. Justice Minister Chris Ellison called the arrests "a major breakthrough" in efforts to crack the Islamic militant network.