Italy on Sunday ordered migrants aboard a rescue ship off its coast to be quarantined on another vessel to test them for the coronavirus instead of allowing them to disembark.
The Alan Kurdi, run by the German non-governmental group Sea-Eye, is sailing in international waters off the western coast of Sicily.
The transport ministry said in a statement those on board will be transferred to another ship, screened by health authorities and quarantined on that ship.
This week the government closed ports to charity boats for the entire duration of the national health emergency over the coronavirus, a ban due to remain in effect until July 31.
The transport ministry statement said allowing the migrants to disembark would put too much pressure on already stretched health services in Sicily. It gave no details on the planned transfer, its timing or location.
After a relative lull in arrivals of boat migrants from Africa, numbers had started to pick up again in the first two months of the year, only to fall back sharply in March as Italy was hit by the epidemic.
However, smaller boats with migrants continue to arrive in Italy. A dinghy carrying about 100 migrants arrived at the Sicilian town of Pozzallo on Sunday morning, local authorities said.