Tan, who was suffered minor injuries in the "human bomb" blast, said he suspected his rivals had ordered the attack.

"It is not just a coincidence that this bomb exploded right next to me," Tan, whose son was hit by the severed head of the suspected bomber.

He told local television channel ABS-CBN that he believed rival politicians with links to "terrorists" orchestrated the attack, and that he suspected the same people were behind an attempt on his life in May last year.

"I have received intelligence reports that I would be bombed," Tan said. "I really would not know if it was a suicide bombing or was it triggered by someone else. But it was a human bomb."

Construction worker

There was no immediate claim of responsibility for the attack.

The Philippines military said the suspected attacker was a local construction worker, and not affiliated with any extremist group.

The military said suspected attacker was not linked to any extremist group [EPA]

"The indications are it is not a suicide bomber," Lieutenant-General Benjamin Dolorfino, the regional military commander, told the AFP news agency.

"The possibility is someone sent [the man] with the backpack and he did not know what was inside.

"You can see him on [security video footage]. He was just standing outside the airport arrival area just before the blast. He was just loitering there."

The bombing occurred on the eve of a planned visit to Zamboanga by Harry Thomas, the US ambassador to the Philippines, who was set to inspect local projects funded by US aid money.

Thomas immediately cancelled his trip and condemned the attack, offering US assistance in catching the perpetrators.