The Air Force's Boeing 757 has broken down in Melbourne, stranding media and forcing the Prime Minister on to last minute commercial flights.

Photo: RNZ / Demelza Leslie

Jacinda Ardern was in Australia for talks with her Australian counterpart in Melbourne and was due to fly back this evening.

But as journalists arrived for the flight, they were told the plane had broken down.

The aircraft had some mechanical issues before the trip, but was given the all-clear after last-minute repairs.

It was not clear if the original problem was responsible for today's cancellation.

The Prime Minister's party has been moved onto commercial flights, and accompanying media were also trying to secure return flights.

Former Prime Minister John Key ran into similar problems in 2016 when a 757 broke down in Townsville, Australia.