Updated 2.52pm -

Six EU countries are ready to take in some of the migrants currently stranded on board the migrant rescue ship Open Arms off Lampedusa, Italian Prime Minister Giuseppe Conte announced on Thursday.

"France, Germany, Romania, Portugal, Spain and Luxembourg have told me that they are ready to welcome the migrants," Conte said in an open letter addressed to Interior Minister Matteo Salvini.

Earlier, Italy's defence minister blocked a new decree by Salvini to ban the Open Arms with 147 migrants on board from Italian territorial waters, in a move seen as part of the political crisis in Rome.

Salvini earlier this month signed a decree banning the Spanish charity Proactiva's Open Arms from Italian waters, saying it was needed to protect public order. 

But Proactiva appealed to an administrative court which on Wednesday suspended the decree.

Salvini then signed another decree blocking the ship but his power has weakened since he withdrew his support last week from the coalition government between his far-right League party and the anti-establishment Five Star Movement (M5S).

On Thursday Defence Minister Elisabetta Trenta, a M5S party member, who must sign off on Salvini's decree, announced that she has decided not to do so. 

"I took this decision for solid legal reasons, listening to my conscience," Trenta said in a statement.

"We must never forget that behind the polemics of the past few days, there are children and young people who suffered violence and abuse of all types. Politics must never lose sight of humanity."

The humanitarian rescue ship Open Arms was anchored Thursday off the Italian island of Lampedusa.

The migrants had been plucked from boats in the Mediterranean this month with weather conditions encouraging more departures from Libya.

Both Italy and Malta have refused Open Arms permission to dock and unload its passengers.

On Wednesday, however, Trenta dispatched two ships to escort the Open Arms out of concern to evacuate the 32 minors after two weeks on board.

- No plan to use force -
Proactiva said it was assured that she does not plan to use force against the migrant ship.

Another rescue ship the Ocean Viking, operated by SOS Mediterranee and Doctors without Borders (MSF), which is also looking for a port to dock with more than 350 migrants on board, was on Thursday between Lampedusa and Malta.