By Mohammad Anwar

KUNAR, Afghanistan (Reuters) - An Afghan army special forces commander has defected to an insurgent group allied with the Taliban in a Humvee truck packed with his team's guns and high-tech equipment, officials in the eastern Kunar province said on Sunday.

Monsif Khan, who raided the supplies of his 20-man team in Kunar's capital Asadabad over the Eid al-Adha religious holiday, is the first special forces commander to switch sides, joining the Hezb-e-Islami organization.

"He sent some of his comrades on leave and paid others to go out sightseeing, and then escaped with up to 30 guns, night-vision goggles, binoculars and a Humvee," said Shuja ul-Mulkh Jalala, the governor of Kunar.

Zubair Sediqi, a spokesman for Hezb-e-Islami, confirmed that Khan had joined the group, saying he had brought 15 guns and high-tech equipment.

The NATO-led coalition is grappling with a rise in "insider attacks" by Afghan soldiers who turn on their allies, undermining trust and efficiency.

It has reported four lethal incidents over the past month taking the total number this year to 10, according to a Reuters tally.

Kunar, like other provinces along the border with Pakistan, is among the more insecure and volatile parts of Afghanistan.

Local security forces have started a manhunt for the commander and tribal elders have promised to help.

"We are trying our best to use elders' influence in that area to bring back all equipment," Jalala said.

A record number of insider attacks - accounting for about one in every five coalition combat deaths - last year prompted the coalition to briefly suspend all joint activities and take steps to curb interaction between foreign and Afghan troops.

That has cut down the number of incidents, but some soldiers say the measures have further eroded the trust painstakingly nurtured between the allies over more than 12 years of war.

All entrants to the Afghan National Security Force have to pass an eight step vetting process, which includes providing identification cards, letters of recommendation by village or district elders and undergoing tests.

(Writing by Mirwais Harooni; Editing by Jessica Donati and Anthony Barker)