Fire crews has destroyed a fishing vessel in Milford Sound.

Fire and Emergency received a call shortly after 4am to the boat at Fisherman's Wharf in Deepwater Basin.

The Milford Sound Fire Brigade fought the blaze with Te Anau firefighters, who were sent in by helicopter, and with the help of local fishermen.

The boat was burned through and crews were are working to put out the remaining flames.

Fire and Emergency spokesperson Lyn Crosson says the fire caused several gas bottles on board the ship to explode.

Shane Nyhon and his crew had been out fishing for cray and were near to the boat when it caught fire. His wife Amber Nyhon said he alerted Fire and Emergency, then worked to save another boat close by from catching alight by cutting the rope tied to the dock.

There was no-one on board the boat and no injuries, a Fire and Emergency spokesperson said.

The blaze is not being treated as suspicious.

Southland Harbourmaster Lyndon Cleaver said it was lucky the boat was steel-hulled otherwise the fire may have burned to the water line and released contaminants into the water.

They are working to make the boat water tight as soon as possible.

Southland Regional Council said there was no immediate evidence diesel or other contaminants were leaking into the water, though an environmental risk will remain until the boat can be made watertight.

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