At least five fire crews battled a blaze on the Dong Won 701 when it caught fire on the evening of April 9, 2018.

Witnesses report hearing a loud bang when a fishing ship caught fire at the Timaru Port.

Ten fire crews and a tug boat are fighting the blaze at the front of the 81-metre Dong Won 701 fishing vessel docked next to the San Won building.

Fire and Emergency NZ southern communications shift manager Tim Reynolds said 10 fire crews including one from Christchurch were responding to the incident, which started about 9.25pm.

JOHN BISSET/STUFF The ship is docked next to the San Won cool stores building in Timaru.

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He said the ship, the Dong Won 701, was "well involved in flames", but all persons from the ship were accounted for.

JOHN BISSET/STUFF Firefighters from around South Canterbury are being called to the burning ship in Timaru's harbour.

Reynolds said fire crews were still actively dealing with the fire as of 11.50pm, and had not confirmed it was contained yet.

He said the size of the response was due to the size of the fire, and he expected at least some of the crews would be there overnight.

A St John spokesman said three patients had been taken to Timaru Hospital with minor injuries. They were checked for smoke inhalation.

SUPPLIED Emergency services are responding to a large ship fire at Timaru Port.

A police spokeswoman said emergency services were called to the fire about 9.25pm.

Police were there as "essentially a bit of crowd control on land", she said.

Soosie Lucas, who lives opposite the port, said there was a "loud bang" when the ship caught fire.

JOHN BISSET/STUFF Fire crews battle to bring a fire under control on a fishing boat in the port of Timaru

"It boomed all around the port, it was a big loud bang."

Lucas said "very thick and dense" smoke was spewing from the ship when the fire started, but it had been dampened down by the rain.

There was a traffic jam forming from people coming down to look at the fire, Lucas said.

An eyewitness said there was "a heavy emergency services presence", with at least five fire trucks, a command unit, and three ambulance on scene.

She said a crowd of people were looking on from behind the fence, despite the cold and rainy night.

The Dong Won 701 is a South Korean fishing vessel which arrived in port on Monday morning, and was due to leave on Tuesday. It was one of the boats involved in an employment court action in 2014 for paying crew below the minimum wage.

Its owned by Korean fishing company Dong Won Fisheries. Its website said it has over $150 million USD annual revenue, operates a seafood processing plant in China, and a specialised seafood processing company in called San Won in Timarua [sic], New Zealand.