Firefighters were called to the scene at around 5.30am after reports the large dredging vessel was leaning to one side and filling with water.

But it proved too late to save the boat.

Harbour workers had already bunged up any fuel holes and points where diesel or other hazardous materials could leak out.

Despite this, a small amount of diesel leaked out..

Fire crews put a floating device around the sinking vessel and successfully contained the leakage to be later pumped away.Teams from Lancaster, Morecambe and Preston Fire Stations attended the scene, along with a hazardous materials unit from Blackpool.

Steve Darby, Morecambe Fire Station watch manager, said: "The boat crew's actions saved fuel leaking from the vessel, and the fire crews contained any fuel that did get out.

"The actual fuel that did escape was a relatively small amount but looked a lot more once it had dispersed on top of the water.

"All in all it was a successful operation."

It is not known what caused the leak in the vessel.

It will now be up to insurance and salvage companies to decide how the boat is removed from the water.