A Spanish aid group says the health of 105 migrants rescued in the Mediterranean Sea is at risk because Italian and British maritime authorities are not allowing their transfer to a safe port.

Proactiva Open Arms says it has been unable to hand over the migrants —including six children and 32 unaccompanied teenagers— from their sailing vessel, Astral, to a bigger and better-equipped rescue boat Monday.

The Astral sails under a British flag. Its captain, Riccardo Gatti, blamed "bureaucracy" and said that neither the Italian coast guard nor the National Maritime Operations Center in Britain had issued a written authorization for the transfer more than 30 hours after the migrants were rescued from a rubber boat.

The Italian and British authorities didn't respond immediately to requests for comment.