Ministry of Defence police stormed a Greenpeace vessel blockading the nuclear base at Faslane in the Firth of Clyde last night.

Around 20 officers with battering rams clambered aboard the Arctic Sunrise at about 5.15pm while it was anchored outside the naval base, protesters on board the vessel said.

Around 20 activists on Arctic Sunrise refused a series of requests by Ministry of Defence police to move the vessel - 300 metres from the Trident nuclear submarines - stating they had no intention of leaving.

Ben Stewart, a spokesman for Greenpeace, said police officers managed to get on board after an hour of cat-and-mouse manoeuvres.

Speaking from the hold of the vessel after the boarding, he said: "The police have just boarded and smashed their way on to the bridge. We think they have taken over the bridge, with all the navigation and steering gear. The MoD is trying to take control of the ship, but the captain is resisting."

Mr Stewart said the captain was on the bridge with three crew. The remaining 15 crew members locked themselves in the hold of the ship, he said.

A Royal Navy spokesman said the MoD police had taken control of the vessel at 5.25pm precisely. Officers were in the process of motoring the ship inside the naval base to a waiting berth, where the protesters will be dealt with, he added.

He said no resistance was encountered while on board the Arctic Sunrise and added that the commanding officer of the Arctic Sunrise was a former Argentinian naval officer.

The Greenpeace activists sailed into the restricted area of Faslane at around 8am yesterday. Mr Stewart said the action was timed to coincide with the visit to the base of a delegation of Labour MPs.

The 164ft-long former icebreaker dropped anchor at lunchtime.

Arctic Sunrise was accompanied by other protesters in six rigid hull inflatable boats. At least 16 people were arrested during the morning after police in boats moved in to tackle the smaller craft.

Protesters aboard the vessel said they were expecting to be arrested in the event of the boat being stormed by police, bringing the total of arrests to around 40.

The detentions yesterday are the latest of hundreds that have taken place outside the Faslane base over the years. Protesters are angry at government plans to renew the Trident weapon system at an estimated cost of £20bn.

Faslane, on the Gare Loch, is home to the UK's fleet of Trident nuclear submarines.

The Westminster parliament is due to formally decide next month whether to give the Trident renewal the go-ahead.

Royal Navy officials said at no time had the security of the naval base been breached.