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Passengers waited nervously as their plane circled Blenheim airport this morning before making an emergency landing.

The twin-engine plane with 17 people on board made a belly-landing at the town's Woodbourne airport around 9.15am.

One passenger, Natasha Frisby, said the plane - travelling from Timaru - was close to Wellington before the pilot announced there was a problem and that it would be diverted to Blenheim.

Ms Frisby, a health promoter going to Wellington for a conference, said she was not initially concerned but things got more tense when the pilot told passengers the wheels would not release and to tighten seatbelts and brace for a rough landing.

She said there were a few nervous laughs before passengers began following instructions.

There was a loud bang when the plane hit the runway and it quickly ground to a stop.

"It was a bit frightening," she said, but there was relief that the plane didn't catch fire.

Ms Frisby said passengers were this morning in the process of sorting out alternative travel arrangements and that she was heading to Nelson on a bus to get a connecting flight to Wellington.

The Beech 1900 plane landed without injury to any of the passengers.

A witness said it landed on its belly and was immediately met by fire appliances and sprayed with foam.

He said it came to a stop about halfway down the runway and had gone down smoothly and managed to stay straight for the length of the landing.

Woodbourne airport warrant officer Ross Connochie said there were no sparks as the plane skidded to a halt.

"It was a very clean landing, it came in very slow and smooth."

Mr Connochie said some propeller tips had snapped off and there would be some scrapes on the underside of the aircraft.

He said he had spoken to some of the passengers, who told him that waiting while the plane circled the airport had been more nerve-racking than the landing.

"They said they all talked to each other, swapped a few seats around, and the pilot came and had a chat to them and made sure everyone was comfortable.

"All the hand baggage was put in the front of the plane and everyone knew what they were going to do."

The passengers were full of praise for the pilot, Mr Connochie said.

One of the passengers was a pregnant woman who was taken to hospital for observation but not believed to have been harmed.

Authorities temporarily closed the airport to all planes other than those that could land on grass and cranes were called in to shift the aircraft.

The aircraft would remain on the runway for a few hours, he said, until cranes arrived to lift it onto a large flat deck trailer to be removed.

The incident is being investigated by aviation authorities.

Once the fire risk was over a mini-bus was driven out to the plane to pick up the relieved passengers and take them back to the airport's military terminal.

Air New Zealand said no one was injured in the incident and everyone on board was being supported at the airport.

The plane was operated by Air New Zealand subsidiary Eagle Air.

- NZPA