Our soldiers killed by 20kg bomb

It was a bomb that weighed more than 20kg which killed the three New Zealand soldiers in Afghanistan on Sunday.

PHOTOS: NZ soldiers killed in Afghanistan

Prime Minister John Key says it could have been made by the same Taliban expert who was being hunted a fortnight ago when two soldiers were killed in a firefight.

"Obviously this bomb maker, if he is the person responsible for the deaths of our soldiers, is very sophisticated," Mr Key said on Monday.

"It was a very large bomb, over 20kg as we understand. We need to intercept him and ensure he can't carry on with his activities."

Mr Key says New Zealand's Provincial Reconstruction Team (PRT) in Bamyan province needs better information about Taliban activities in neighbouring Baghlan province, where a Hungarian PRT operates.

"We are working alongside the Hungarians, their focus has been in the northern part of Baghlan," he said.

"Insurgents have been able to get a foothold in southern Baghlan and that's where New Zealand may increase its patrols... if we're more proactive they're less likely to be able to get established and lay their bombs in the ground."