'The government is assessing this issue very seriously and why they were forced to carry out a suicide mission,' presidential spokesman Seyamak Herawi said.

'We are investigating it seriously. At this moment, we can only confirm that only one of the two suicide bombers was pardoned by President Karzai last year.'

The two boys were arrested in the southern city of Kandahar as they were preparing to blow themselves up, officials said.

'Kandahar's intelligence agents arrested two child suicide bombers and three other insurgents during an operation late last week,' an intelligence official said.

'The suicide bombers went to Quetta city of Pakistan and received training to carry out suicide bombings,' the official said. 'One of the children is a resident of Pakistan's Balochistan city and the second one is a resident of Paktia's Gardiz city.'

On Sunday, they were brought in front of local media in Kandahar city where they confessed to being trained in a religious school in Pakistan.

A boy named Azizullah said mullahs at a Quetta madrasa had told him to go to Afghanistan and carry out the suicide mission.

The other, named Nasibullah, said he was deceived by insurgents and asked the Afghan government to pardon him once again