Indonesian police investigating the Bali blasts have identified a key suspect as the chief planner of the attacks and said he learned bomb-making in Afghanistan.
Major-General Mangku Pastika, head of a multinational investigation team, named Imam Samudra as the field co-ordinator who decided where to place the bombs in a crowded night club district.
A man, named Dulmatin, triggered the bombs by mobile phone. Pastika told a news conference that Dulmatin helped assemble the bombs that killed nearly 200 people.
Police in the world's most populous Muslim nation have made significant progress in the Bali probe in the past two weeks, beginning with the arrest of one man named Amrozi who has confessed to involvement in the blasts.
They do not know the whereabouts of the other six suspects, all Indonesians, but have released a combination of photographs and sketches of the suspects. When asked whether police had any idea of the location of any of the suspects, Pastika said: "I cannot disclose the predicted places yet. It's too sensitive."
Police have said they have been hunting for a group of about 10 bombers, most of them militant Muslims, who wanted to kill as many Americans as possible. Up to 90 Australians were among the dead. Police have not said if the group took orders from others, but suspicion has fallen on Jemaah Islamiah, a Southeast Asian militant Muslim network linked to Osama bin Laden's al Qaeda.