A group of 15 rescued migrants arrived in Spain on board a Spanish warship after Italy refused to allow the rescue vessel that had picked them up in the Mediterranean Sea to dock at an Italian port.

The migrants, part of a larger group of over 100 people rescued by Spanish-registered boat Open Arms and then stranded off Italy for three weeks, were seen walking ashore in the port of San Roque in southwest Spain and board a bus under police escort.

The 15 people - 14 men and a woman - will undergo health checks and will be granted provisional permits until their asylum applications have been resolved, Spain's government said in a statement.

Spain dispatched the ship last week to pick up the migrants after five EU countries agreed to take them in following a prolonged standoff between the OpenArms and Italian authorities.

Italy's outgoing far-right interior minister, Matteo Salvini, has banned ships carrying illegal migrants from docking at Italian ports in an attempt to stem the flow of people trying to cross the Mediterranean to Europe from north Africa.

The Spanish Navy warship Audaz that carried the 15 migrants

Rights group Amnesty International said this week the Open Arms saga, one of a number of similar cases, underlined Europe's failure to come to grips with the migration crisis.

The handling of the issue by Spain's caretaker Socialist government drew criticism at home during a special parliamentary session on yesterday.

Some parties criticised the government for accepting the migrants and others for not doing so more quickly.

Another charity vessel banned from entering Italian waters has warned of an impending health emergency on board.

Charity Mediterranea Saving Humans said it had sent a "new urgent request" for a safe port for its Mare Jonio ship, "due to the risk of a health and sanitary emergency".

Sixty-four vulnerable people including women and children were disembarked yesterday, leaving 34 migrants on board.

Particularly worrying was a "lack of water for hygienic and other on board needs", the charity said in a statement.

Meanwhile, Ireland was among the five other countries to agree to relocate migrants stranded on board the Ocean Viking in the Mediterranean.

France also took 150 of the migrants, while Germany, Luxembourg, Portugal and Romania also agreed to relocate them.

The migrants, mainly from Africa, were removed from the boat after an Italian prosecutor ordered the seizure of the ship and the evacuation of the people.