Two top leaders of a banned pro-Taliban group, which brokered the controversial Swat peace deal, were killed on Saturday in Pakistan's restive northwest when militants ambushed a security forces' convoy transporting the detained extremists to a prison in Peshawar.

Maulana Muhammad Alam, deputy chief of Tehrik-e-Nifaz-e- Shariah Muhammadi (TNSM) which is headed by radical cleric Sufi Muhammad, and the group's spokesman Amir Izzat Khan were killed along with a non-commissioned officer in the attack which occurred at 5.10 am local time in the troubled Malakand area, the military said. Five soldiers were also injured.

The convoy was transporting several prisoners arrested during the anti-Taliban operation in Swat and nearby areas to a jail in Peshawar when it was attacked by the militants.

Three TNSM leaders, including Khan and Alam, were arrested on Thursday along with three Afghan militants when troops raided a seminary at Amandarra, the headquarters of the banned organisation. Khan and Alam were among those being transported to the Peshawar prison.

Sufi Muhammad, who was also reportedly arrested on Thursday along with his two sons, had mediated between Taliban fighters led by his son-in-law Maulana Fazlullah and the North West Frontier Province government and finalised a peace deal whereby authorities agreed to set up Islamic courts in Swat in exchange for the militants laying down their arms.

However, the Taliban did not observe the terms of the peace agreement and began intimidating and killing people in nearby districts.

Sufi Muhammad also sparked a controversy by announcing at a rally that democracy, the judiciary and parliament were "un-Islamic."