ASADABAD, Afghanistan (AFP) - A US-trained Afghan special forces commando has defected to an insurgent group, taking with him an armoured vehicle full of weapons and ammunition in the eastern province of Kunar, officials said on Monday.

"He left his base and drove to his home district to join Hezb-i-Islami," Kunar governor Shuja-Ul Mulk Jalala told AFP, referring to an insurgent group that fights alongside Taliban militants.

Mr Museeb Khan was an officer in a special force unit assigned to conduct complex operations against the Islamist rebels who wage a guerrilla war against US-led Nato forces and the Kabul government.

The defection will be a blow to the development of the country's special forces as they increasingly take on high-target missions from elite US soldiers ahead of the coalition's withdrawal by the end of next year.

Mr Jalala said a manhunt had been launched to find the commando, who also escaped with some unidentified military equipment.

Zubair Sediqi, a purported Hezb-i-Islami spokesman, told AFP that the officer had been in contact with the group before his defection. He gave no further details.