The attack that killed three soldiers in Afghanistan today is not part of a targeted campaign by the Taleban, the International Security Assistance Force says.

The Defence Force today confirmed three soldiers were in the last vehicle of a convoy when they were hit by an improvised explosive device in Bamiyan yesterday.

The deaths come only two weeks after Lance Corporals Rory Malone and Pralli Durrer were killed during a firefight in the same area.

The soldiers were all from the Provincial Reconstruction Team, which is part of the ISAF.

Despite the Taleban taking responsibility for both attacks, ISAF spokesman Captain Daniel Einert said it didn't appear to be the beginning of a trend.

"I don't think there is anything based on our operational reports that would indicate that that is the case," he said.

"It's a very unfortunate situation that has re-occurred."

However, specialist New Zealand troops have arrived in Afghanistan following the deaths of Durrer and Pralli.

Prime Minister John Key told TVNZ's Breakfast the group was sent because of increased bomb-making activities in the area.

Key reiterated his comments that it was unlikely the SAS would be sent back into Afghanistan as a fighting contingent, but an SAS logistics officer would also be sent over.

The insurgents were from the neighbouring Baghlan province, Key said.

Bamiyan is one of the quieter provinces in Afghanistan, where the greatest challenges had been the climate and appalling roads.

There have been signs of a growing military threat however, particularly in the northeast, where the latest killing took place.

Einert said he couldn't give much detail as to why these attacks had taken place.

The ISAF commanders were taking the attacks seriously, and looking at what can be done to prevent another in the future, he said.

"I can't tell you specifically what is being done."

- © Fairfax NZ News