Taliban attackers killed more than 100 Afghan security personnel when they detonated a car bomb in a training base and then stormed inside.

The deadly attack on an intelligence training centre came amid American fears that the beleaguered Afghan forces are suffering unsustainable casualties against the Taliban.

A captured, American-made armoured vehicle loaded with explosives was rammed through a checkpoint at the National Directorate of Security (NDS) training base in Maidan Shahr, the capital of Maidan Wardak province.

A senior defence official told Reuters that after the vehicle detonated in the campus, two gunmen had entered and shot dead many Afghans in the wake of the huge explosion.

"We have information that 126 people have been killed in the explosion inside the military training centre, eight special commandoes are among the dead," said the official.

Another official put the NDS death toll at more than 100.