Hundreds of people on board a rescue boat funded by street artist Banksy have been transferred to safety after the vessel became stranded in the Mediterranean Sea.

The boat – named Louise Michel – was unable to move due to an overcrowded deck after picking up 219 migrants off the Libyan coast since Thursday.

The vessel, which had a dead body onboard, was left stranded off the coast of Malta for around 12 hours into Saturday, organisers said.

The Italian Coastguard told Sky News it had stepped in to transfer 49 of the “most vulnerable” on board to safety on Saturday afternoon.

The coastguard also collected the body of the male who died before the Louise Michel could reach a rubber boat a day earlier, the crew of the Louise Michel said.

Another humanitarian ship called Sea-Watch 4 has since taken all the remaining people on board, they added.

A tweet from the Louise Michel account said: “Just transferred all remaining guests onto #SeaWatch4, who now have about 350 people on board. It’s not over: We demand a Place of Safety for all survivors, now.”

The boat’s crew had earlier been close to declaring “a state of emergency” after claiming European officials ignored repeated calls for help.

The 31-metre-long motor yacht, which is a former French navy boat, features some of Banksy’s trademark work, including a girl in a life vest holding a heart-shaped safety buoy.

The vessel, named Louise Michel after a 19th-century female French anarchist and teacher, was being used to help migrants in the Mediterranean trying to reach Europe from North Africa.

It was bought with the proceeds of some of Banksy’s works and is captained by a professional crew with a “flat hierarchy and a vegan diet”.

The British street artist reportedly first made contact with Pia Klemp, an experienced captain of a number NGO boats, in September 2019 asking to help.

On Friday morning, the crew said they had rescued 89 people, including 14 women and four children, and were seeking a place of safety for them to disembark.

That evening, the vessel lent assistance to another overcrowded boat filling with water which had a dead body on board and many people suffering fuel burns.

The crew claimed they put emergency calls out to agencies from Germany, Malta and Italy but were ignored.

They posted a video of the overcrowded boat, writing: “These are the survivors you are turning your back on #EU. After escaping untold horror and inhumanity they need a place of safety.”

A crew of 10 European activists were on the Louise Michel, which last week left Burriana in Spain and had sailed to an area about 90 miles southeast of the Italian island of Lampedusa.

It was supposed to carry a maximum of 120 passengers.

Banksy posted a promotional video on his official Instagram page, with the words “Like most people who make it in the art world, I bought a yacht to cruise the Med” overlaid with pictures of Louise Michel and migrants in distress.

“It’s a French navy vessel we converted into a lifeboat because EU authorities deliberately ignore distress calls from ‘non-Europeans’,” the video continued.

The boat’s launch on 18 August was kept secret and news of the mission was only released following its first rescue.

While it is fairly small, the yacht has a top speed of 27 knots and so is considerably faster than other NGO rescue vessels.

On Wednesday, 45 people – including five children – died when the engine on their boat exploded off Libya, in the country’s deadliest shipwreck this year.

More than 7,600 migrants have been discovered at sea and returned to Libya so far this year, according to figures from the International Organisation for Migration.