Updated

Humanitarian groups urged the Italian government Tuesday to allow 177 migrants aboard an Italian coast guard ship docked at the Sicilian port of Catania to be permitted to disembark.

Doctors Without Borders, the U.N. refugee agency and Save the Children have all appealed to the government to let the migrants off the ship for humanitarian and medical reasons.

The Italian coast guard ship Diciotto arrived in Catania late Monday, but the Italian government won't let them off the ship until it has pledges from other European countries to take them, in the latest standoff over migrants being rescued at sea.

The migrants rescued last week have been on the boat about six days.

Doctors Without Borders said its team is standing by to offer psychological assistance to the migrants, urged Italy "to allow disembarkation so that rapid treatment can be given."

Giovanna Benedetta of Save the Children noted that many of the migrants aboard the ship had been detained in Libya for months before the passage on overcrowded smugglers' ships and were traumatized. Twenty-eight are unaccompanied minors.

And Carlotta Sami of the U.N. High Commissioner for Refugees tweeted that "they have an urgent need to receive assistance and to ask for asylum. It is a fundamental right, not a crime."

Malta has declined to take them, saying the smugglers' boat they were in wasn't in distress as it passed Maltese waters and that, in any case, the migrants preferred to continue to Italy.

Italy has asked the EU to work out a solution and follows a threat by Interior Minister Matteo Salvini to send them back to Libya.