JAKARTA (AFP) - Indonesian police said they had four suspects under arrest in relation to the deadly bombing at the Australian embassy, including three detained before the blast for links with a fugitive Malaysian bomb maker.
National police chief General Da'i Bachtiar said nine other people were being questioned and some of them could emerge as suspects.
"With the arrest of these people our investigation has become more focused," Bachtiar told a press conference on Saturday.
The detainees were only identified by their initials.
Police Saturday also issued the sketch of the last buyer of a truck used in the September 9 bombing, which killed at least nine people and injured more than 180.
Bachtiar said the man's facial features were similar to a terror suspect on a police wanted list.
Police suspect one or more suicide bombers were in the truck when it exploded.
The police chief also said one of the four suspects under arrest, identified by the initials A.H., had been tasked with transporting explosive materials by Azahari Husin, a Malaysian bombmaker suspected with compatriot Noordin Mohammad Top of masterminding the embassy attack.
"He is very close to Azahari," he said.
Azahari and Noordin have been associated with the Al-Qaeda-linked Jemaah Islamiyah group blamed for several attacks, including the October 2002 Bali bombings which killed 202, and one last August on Jakarta's Marriott hotel that killed 12.
The three other suspects had been arrested before the bombing for allegedly harboring Azahari, Bachtiar said.
Under tough anti-terror laws introduced in the wake of the Bali bombing, suspects can be held for up to six months without being charged.
Australian and Indonesian police have warned of further attacks in Jakarta, naming Western embassies, hotels and apartment blocks catering to foreigners as potential targets.
President Megawati Sukarnoputri has placed the country on "full alert" following the embassy blast and ahead of September 20 elections, deploying an extra 200,000 police to sensitive locations.
Meanwhile, alleged Jemaah Islamiyah leader Abu Bakar Bashir condemned the embassy bombing and accused Canberra of trying to put the blame on him.
"I condemn the bombing which claimed the lives of innocent victims and caused big destruction," Bashir said in a statement read by his lawyer Wirawan Adnan.
Bashir, who is awaiting trial for his alleged role in earlier bomb attacks, said terrorists "must be punished and stopped for good."
The cleric described as slander Australia's claim that Indonesian police had received an SMS warning of an attack minutes before the blast. The message allegedly demanded Bashir's release.
"This slander is utterly incredible. Is it that difficult to verify the truth about an SMS? If there is indeed an SMS, why did the Indonesia police reported it to Alexander Downer? Is he now their boss?" Bashir said.