Police released a grainy photo Friday of a white delivery truck taken by a security camera just before it blew up outside the Australian Embassy and said they suspect two homicide bombers in the vehicle set off the explosion, killing seven other people.

As details emerged in the attack, Australian Foreign Minister Alexander Downer said at a Jakarta news conference that Indonesian police had received a mobile phone text message 45 minutes before the bombing, warning that foreign missions in Jakarta would be attacked unless the alleged head of Al Qaeda-linked Jemaah Islamiyah (search) was freed from prison.

Australian officials said the threat was not passed on to Australian Federal Police until hours after Thursday's bombing. But Indonesian police said they had received no such warning.

"That's not true. Where did Downer get that from?" said Indonesian police spokesman Maj. Gen. Paiman, who goes by a single name.

In Australia, Prime Minister John Howard (search) said another attack in Jakarta was a "distinct possibility." Militants have repeatedly struck foreign targets in Indonesia, the deadliest in 2002 when they bombed nightclubs on Bali, killing 202 people, including many Australians.

"There has been a lot of 'chatter' as the intelligence agencies call it, and a lot of evidence coming forward suggesting it," he said of another attack.

The accused head of Jemaah Islamiyah, Abu Bakar Bashir (search), is in jail as prosecutors draw up a revised indictment against him for allegedly inspiring his followers to launch attacks. In 2002, an Indonesian court cleared Bashir of terror charges, but sentenced him to 18 months in jail for minor immigration violations. He was rearrested in April after serving his sentence.

A claim of responsibility in Jemaah Islamiyah's name was posted Thursday on an Internet site known for carrying extremist Islamic content. Its authenticity could not be verified.

"We decided to call Australia to account, which we consider one of the worst enemies of God, and God's religion of Islam," the statement said. "Here we were able to call it to account today in Jakarta, where one of the mujahedeen (holy warriors) was able to execute a martyrdom operation with a truck bomb in front of the embassy."

Jemaah Islamiyah has also been blamed for the bombings at Bali and against the JW Marriott hotel in Jakarta a year ago, which killed 12 people.

The Australian Embassy attack, which also injured more than 170 people, struck a key U.S. ally in the war in Iraq. It came just ahead of the Sept. 11 anniversary, shortly before Indonesia's Sept. 20 presidential election, and ahead of Australian parliamentary polls on Oct. 9 in which Howard is running in a tight race on a pro-American, anti-terror platform.

Police said the delivery truck was packed with 440 pounds of potassium chloride. Authorities said they recovered a vehicle chassis and other parts.

Indonesian police chief Dai Bachtiar said authorities were searching for two key alleged members of Jemaah Islamiyah — suspected Malaysian bomb-makers Azahari bin Husin and Noordin Top. Police discovered an empty house near the airport rented last month by the suspects.

Lt. Gen. Suyitno Landung, the national police's chief of detectives, said information about the bombers came from interrogations of six men arrested in June. Police also recovered letters in which a bomber asked his family permission to take part in an attack.

Australian forensics experts and bomb experts joined Indonesian police at the bomb site Friday, marking evidence on the road by putting small orange flags on bits of bomb debris.

Bouquets of flowers lined the front of surrounding buildings along with posters saying: "Today, Indonesia is crying," and "Curse the terrorists!"

Australian leader Howard has come under fire for sending 2,000 troops for last year's U.S.-led invasion of Iraq, and still has more than 850 military personnel in or around the country. The Iraq war is deeply unpopular in Indonesia, the world's most populous Muslim nation.

But some analysts predicted the bombing could help Howard's government in next month's polls against the Labor Party because it is seen as stronger on security issues.

In Indonesia, analysts predicted the bloodshed could further alienate Indonesians from Jemaah Islamiyah and decrease the already-waning support for conservative Islamic political parties which fared poorly in April parliamentary elections.