VALLETTA, Oct. 20 (Xinhua) -- The NGO humanitarian ship Sea-Watch departed from Malta on Saturday after having been prevented from leaving the island by the Maltese authorities for more than three months, the organization said.

The ship was being used to rescue African migrants who were stranded at sea while attempting to flee to Europe.

The vessel said on social media that after having been "unlawfully detained," the Sea-Watch 3 was allowed to leave the port on Saturday morning. It is now en route to Spain.

The ship had been held in Malta after a dispute among European Union member states over the fate of a group of migrants rescued by another humanitarian vessel operated by a different NGO, the MV Lifeline.

Earlier in October, the reconnaissance aircraft Moonbird, operated by Sea-Watch, resumed operations after having been grounded in Malta for three months.