Hand said that the four militants were going to plant a mine under a bridge in the Dand district of Kandahar province in the wee hours of Tuesday.

Acting on a tip-off, he said, a gunship aircraft were deployed in the area and killed them on the spot.

He, however, did not provide further details about the airstrike.

Kandahar, the birthplace of Taliban militants, has been the scene of increasing insurgency over the past couple of months.