"The modus operandi is very similar to other attacks, including the Bali bombings and the Marriott blast," he said. "We can conclude (the perpetrators) are the same group."

Bachtiar said the bombing was likely the work of Husin, a British-trained Malaysian engineer who is one of Asia's most-wanted fugitives. Husin has been linked to numerous bombings in Indonesia, including the Bali blasts.

President Megawati Sukarnoputri cut short a trip to Brunei, where she was attending a royal wedding, and toured the bomb scene.

"I ask all the Indonesian people to unite in fighting terrorism," she said. "Let us all condemn what has been done by (terrorists) because we have seen there are so many innocent victims."

The attack comes in the run-up to presidential elections Sept. 20 in which Megawati is trailing badly in the polls behind her former security minister, Susilo Bambang Yudhoyono. Terrorism is rarely mentioned by either candidate, both of whom are secular nationalists. Analysts say the bombing might benefit the challenger, who is seen as somewhat tougher on security.

Regional security consultant Bob Broadfoot said the militants wanted to make clear that they were able to carry out attacks.

"Governments in the region have done a pretty good job of restricting terrorist groups but that doesn't mean that they have extinguished the problem," he said. "That is what we saw today."