Tonga crisis: NZDF forces to be pulled out 'as soon as possible'

New Zealand SAS troops currently in Tonga are going to be pulled out as soon as possible, Foreign Minister Gerry Brownlee and Defence Minister Mark Mitchell say, as the country dissolves into political turmoil.

King George Tupou VI dismissed Tongan Prime Minister Akilisi Pohiva and dissolved parliament on Friday in an unprecedented move.

A group of New Zealand SAS troops were in Tonga or a jungle training exercise at the time, but they're now being withdrawn so the country can have some "clear air", Mr Brownlee said.

"Tonga is clearly in a process of political transition and it's best we leave them to manage that without the added complication of a military training exercise going on," he said.

"King Tupou VI has exercised his constitutional right to dissolve Parliament and we look forward to learning more in the days ahead about Tonga's plans for governance ahead of November's elections."

The training exercise was a joint effort with Tonga and is an annual exercise, Mr Mitchell said.

Rather than being cancelled, it'll be rescheduled for a "more suitable time in the future".

"The relationship between the NZ Defence Force and the Royal Tongan Defence Force remains strong," Mr Mitchell said.

In a statement on Friday, New Zealand's Ministry of Foreign Affairs said it's monitoring the situation and hopes the situation in Tonga will remain calm.