Two suicide bombers attacked Bhutto, says official

A pair of suicide bombers were apparently behind last week's attack on Pakistan opposition leader Benazir Bhutto, a top intelligence official said today.

The news came as the prime minister expressed optimism that the people behind the plot would soon be brought to justice.

Police had initially said only one suicide bomber participated in the attack, but the official said the two severed heads found at the scene - and the fact that no families had emerged to claim either one - suggested two men were responsible.

"One of the attackers wanted to blow himself up under Benazir Bhutto's truck. When people tried to catch him, he detonated the bomb," he said, quoting witness accounts.

Although Bhutto herself escaped unhurt, at least 136 people-- mostly supporters from her main opposition Pakistan People's Party - were killed in the attack on her heavily guarded convoy in the southern city of Karachi.

"The culprits will be brought to book," said a statement issued today by the office of Pakistani Prime Minister Shaukat Aziz, rejecting Bhutto's request that experts from the US and Britain be invited to help with the investigation.