Jacinda Ardern on campaign trail: 'We'll 'reassess our role in Afghanistan'

Labour leader Jacinda Ardern says she would review New Zealand's contribution to Afghanistan if she became Prime Minister after next month's election.

But she would wait until the current mandate of the New Zealand contribution ended in June next year.

She told reporters in Dunedin she had been given a briefing by the Defence Minister on the Government's announcement today to add another three non-combat staff to the 10 New Zealanders already part of the Nato-led mission.

She described it as "modest" and said she could understand the offering.

"But when I'm in Government I do want to take a wider look at our role in Afghanistan more broadly," she said.

""it is a complex conflict. I think we should constantly reassess our role in such conflicts and that's what we'll do.

"We have tended to take the approach of wanting a UN mandate behind our work and also to play a reconstruction role."

In the 17 years since New Zealand first went to Afghanistan the conflict had changed dramatically "and we need to assess we are playing the right role under the circumstance".

The 10 Kiwis already there are working as mentors and support personnel at the Afghan National Army Officer Academy in Kabul and they will be joined by one of the additional staff.

The other two will work in the Nato mission HQ in Kabul, Defence Minister Mark Mitchell said.

New Zealand has been in Afghanistan since 2001 as part of an international force in the wake of the September 11 terrorist attacks on the United States.

Nato has been asking all countries with a presence there to increase their contribution to address a deteriorating security situation.

Australia announced an additional 30 troops in May, taking their total to 300.

United States President Donald Trump this announced approval for more troops, thought to be about 4000.

Mitchell said the boost was part of an effort to prevent Afghanistan becoming a safe haven for terrorists.

"New Zealand will continue to stand alongside our partners in supporting stability in Afghanistan and countering the threat of international terrorism."

New Zealand's contribution is mandated until 30 June, 2018.