(CNN)Migrants rescued by a boat funded by the British street artist Banksy have been evacuated onto Sea-Watch 4, another vessel that rescues people stranded in the Mediterranean Sea.
Migrants on a Banksy-funded rescue boat have been transferred to another vessel after request for 'immediate assistance'
A Saturday evening post on the vessel's Twitter account said it had "just transferred all remaining guests onto #SeaWatch4, who now have about 350 people on board."
"It's not over," the tweet said. "We demand a Place of Safety for all survivors, now."
The transfer took place after the "Louise Michel," a former French naval ship purchased by Banksy, took 219 migrants onboard and requested "immediate assistance."
Sea-Watch International confirmed on Twitter that its vessel had received the passengers, adding, "we now have (about) 350 people on board who need to disembark in a safe port as soon as possible."
The Italian Coast Guard responded to a distress call earlier Saturday from the Louise Michel and evacuated "49 of our most vulnerable guests," the vessel's Twitter account said.
In a joint statement Saturday, the UN Refugee Agency (UNHCR) and the International Organization for Migration (IOM) said the refugees and migrants on the Louise Michel, Sea-Watch 4 and a third vessel must be allowed to disembark.
"The lack of agreement on a regional disembarkation mechanism, long called for by UNHCR and IOM, is not an excuse to deny vulnerable people a port of safety and the assistance they need, as required under international law," the statement read.
The Louise Michel helped rescue 89 people on Thursday, according to a spokesperson for the vessel.
Its 10-person crew later provided help to a further 130 people, including many women and children," a post on the boat's Twitter account said on Friday evening.
The vessel said in a series of tweets earlier Saturday that it was "unable to move" due to its "overcrowded deck," alleging that no European coastguards have responded to its calls for help. CNN was unable to independently verify this claim.
At that time, the Twitter account said 33 of the passengers remained "on a life raft" with one deceased person in a body bag.
Referring to the refugees it is safeguarding, the boat said they have "experienced extreme trauma" and need to reach a "place of safety."
In an update posted on Twitter on Saturday afternoon, the Louise Michel said its crew members were still waiting for assistance half a day later.
"The crew managed to keep #LouiseMichel stable for almost 12h now. Our new friends told us they lost 3 friends on their journey already. Including the dead body in our one life raft, that makes 4 lives vanished because of Fortress Europe," it said in its most recent tweet.
The pink vessel, named after a French anarchist, aims to "uphold maritime law and rescue anyone in peril without prejudice," according to the project's website.
Banksy spray-painted the boat with a fire extinguisher and also created an artwork of a girl in a life jacket, who is shown stretching out one hand towards a heart-shaped lifebelt.
The image bears a resemblance to the artist's famous "Girl with Balloon" stencil murals.
As well as being customized for search and rescue operations, the Louise Michel is "captained and crewed by a team of rescue professionals drawn from across Europe," the boat's website added.
It is 30 meters (about 98 feet) in length and can travel at a speed of 28 knots per hour.