PESHAWAR: Six soldiers were killed when a Pakistani military helicopter crashed in a restive tribal area bordering Afghanistan overnight, the military said Sunday.

The MI-17 helicopter crash landed at Nawapass in Bajaur district due to a technical fault, the military said in a statement.

'Six soldiers embraced martyrdom. The pilots of the helicopter were injured but are safe and out of danger.'

A senior military official late Saturday told AFP the MI-17 helicopter was returning from a routine supply mission to the border areas of Bajaur when it crashed near Charmung village, killing three people and wounding two others.

Pakistani security forces launched a huge operation against Islamist militants in Bajaur last August. In February, they claimed the area had been cleared, but unrest has continued.