The Aquarius ship picked up the migrants, including 123 unaccompanied minors, 11 other children and seven pregnant women, from inflatable boats off the coast of Libya at the weekend.
Spanish Prime Minister Pedro Sanchez, who took office just over a week ago, has given instructions for the boat to be admitted to the eastern port of Valencia, his office said in a statement.
Italy’s refusal to accept the ship is part of efforts by new interior minister, Matteo Salvini, who is also head of the far-right League, to make good on his electoral promises to halt the flow of migrants into the country.
Malta brushed off the request, saying it had nothing to do with the rescue operation, opening the prospect of a diplomatic rift between the two European Union allies.
“Malta takes in nobody. France pushes people back at the border, Spain defends its frontier with weapons,” Salvini wrote on Facebook. “From today, Italy will also start to say no to human trafficking, no to the business of illegal immigration.”
More than 600,000 migrants have reached Italy by boat from Africa in the past five years. Numbers have dropped dramatically in recent months, but rescues have increased in recent days, presenting Salvini with his first test as minister.
“My aim is to guarantee a peaceful life for these youths in Africa and for our children in Italy,” Salvini said, using the Twitter hashtag “We are shutting the ports”.
European charity SOS Mediterranee said on Twitter earlier on Sunday that its rescue boat Aquarius had taken on board 629 migrants, including 123 unaccompanied minors, 11 other children and seven pregnant women.
The charity said the group of mainly sub-Saharan Africans were picked up in six different rescue operations off the coast of Libya and included hundreds who were plucked from the sea by Italian naval units and then transferred to the Aquarius.