The Aquarius will travel to the port of Valencia on Spain's eastern Mediterranean coast, aid agencies confirmed on Tuesday morning.
Doctors Without Borders (MSF) said 400 of the 629 rescued people had been ordered on to "Italian Navy ships which will then head to Valencia to disembark", meaning 229 will continue their journey on the Aquarius.
The Ministry of Defence said the Spanish Navy would accompany the rescue vessel "if necessary" on its journey to Valencia, "and provide support in Spanish territorial waters".
Spanish journalist Sara Alonso, aboard the Aquarius, said the migrants had now been informed of the plan and that they were "generally enthusiastic" about the idea, despite the longer trip: "We like Spain because it accepts us", one Nigerian woman who had been living in Libya for 12 years told her.
MSF criticised the plan to bring the migrants to Spain, though: "This plan would mean already exhausted rescued people would endure 4 more days travel at sea. The better option would be to disembark the rescued people in the nearest port after which they can be transferred to #Spain or other safe countries for further care & legal processing".
MSF Spain said "political motives now forces these exhausted people to put up with a still longer journey", and that "rescue capacity" in the central Mediterranean would be "greatly reduced" as a result of the Aquarius setting sail for Valencia.
SOS Mediterranee confirmed Valencia was now the designated safe port for the Aquarius and its occupants, and said it was "relieved" that a solution had been found.
"However, results are unnecessary prolongation of time at sea for already vulnerable people & reduction of SAR capacity".
Image: Fresh supplies are loaded on board the Aquarius. (@SOSMedGermany)
Image: MoD statement offering Spanish Navy support to the Aquarius.
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