Updated Monday 11.40

Italian Interior Minister Matteo Salvini has warned migrant rescue ship Aquarius it will again not be allowed to dock in an Italian port, just two days after it set out on a fresh rescue mission.

The Aquarius is heading back to its rescue haunt off Libya after what its operators described as 'an extended technical port call in Marseille'.

The ship has already been at the heart of two stand-offs involving Italy and Malta. Italy banned the ship in June and in August. Malta did likewise in June and after a lengthy standoff the ship ended up having to sail to Valencia where it disembarked some 600 migrants.

Last month the ship was allowed to berth in Malta to disembark 141 migrants after agreement was reached with several EU countries to take the migrants.

Read: Aquarius to be allowed into Malta, migrants to be shared among EU countries

The ship then left for Marseille on August 16.

SOS Mediterranee, which operates the ship together with Medicins sans Frontieres had said at the time that the ship was heading for Marseille following a request by the ship owner in order to clarify political and administrative issues raised by the Gibraltar maritime authorities, under whose flag the ship was registered at the time.

The government of Gibraltar had put Aquarius on notice of removal of its registration after it ignored orders to suspend operations as a rescue vessel and revert to its role as a survey ship, as registered.

While the ship was in Marseille it was announced that it would be registered in Panama instead. 

The Aquarius is the last remaining vessels conducting search and rescue missions in the central Mediterranean, with Italy having shut its ports to NGO ships in June and Malta having denied such vessels permission to leave its ports, citing concerns about ship registration anomalies.

The ship is expected to arrive off Libya in the middle of the week.

Another rescue NGO, Sea Watch, reported on Sunday that it had been alerted to a dinghy in distress with some 100 people on board. It informed Rome rescue coordination centre who in turn called the Libyan authorities, but  nothing had happened. The situation had still not changed on Monday