Jakarta – Vice President Yusuf Kalla said on Sunday the government cannot ban Jamaah Islamiyah (JI), an Islamic militant group blamed for a series of terror bombs in Indonesia, arguing that it has never been recognized under the law in the first place.

Kalla was asked to respond to Australia's demand that Indonesia outlaw JI following the second bomb attack in Bali, which killed at least 23 people including three suicide bombers.

Police have said the suicide bombers were a "new generation" of JI, which the Vice President said was a "formless organization".

"For us, the existence of that organization (JI) is not organized, so how can we disband it," Kalla told the press after closing a batik event at the Jakarta Convention Center. "If we have not recognized it and do not know its members, how can we ban it," he stressed.

However, despite its "formless" existence, JI has often been linked by police investigators with bombers who carried out terror attacks in the past few years.

Kalla said the government would take firm action against any organization found guilty of violating prevailing laws.

Australian Minister of Foreign Affairs Minister Alexander Downer is to travel to Indonesia this week and is expected to lobby the government to ban the regional terrorist network.

JI was blamed for the first Bali attack in 2002 which killed 202 people including 88 Australians, and its alleged religious leader Abu Bakar Ba'asyir was jailed for conspiracy over the bombing, but no action was taken to outlaw it as his terror trial failed to link him with the organization.