GENEVA — Dozens of migrants trying to reach Europe drowned in the Mediterranean on Friday and 100 more were sent back to Libya, the United Nations said, while Italian authorities signaling opposition to more migration from Africa seized a rescue ship.

The UN refugee agency UNHCR said 65 people drowned when their boat capsized off Tunisia, and 101 others who had been picked up at sea were returned to Libya, despite repeated warnings that it is not a safe country to send people back to.

It was one the deadliest shipwrecks involving migrants trying to reach Europe via north Africa this year.

Tripoli, a hub for migrants and refugees hoping to sail to Europe after a perilous trek through the Sahara, has long been a dangerous dead end: Many end up in detention centers or being tortured by their captors while money is extorted from their families, according to UNHCR.

But it has become even more dangerous since forces loyal to Khalifa Haftar began an offensive a month ago on the capital, triggering renewed warfare between rival Libyan factions.

Jan Egeland, head of the Norwegian Refugee Council, said that the international community needed to stabilize Libya and the sub-Saharan countries producing flows of migrants, and stop “fueling the fire by giving generals hope that they can take over”.

Europeans bore part of the responsibility to avoid the “mass hemorrhage of human lives in the Mediterranean,” he said.

“We were shocked that 250 people died crossing the Berlin Wall during a generation of Cold War, and now we seem to accept 2,500 or more people dying per year in the Mediterranean. Again, it is a damning verdict of the so-called European civilization.”

On Friday, Italy let a boat carrying 30 rescued migrants dock at an Italian port but Interior Minister Matteo Salvini said it would be impounded and not let out to sea again.

The migrants, including two pregnant women, a baby and four unaccompanied minors, were picked up by the Mare Jonio on Thursday some 40 miles (64 km) off the coast of Libya as their rubber boat was sinking.

“The last voyage for the boat ... Mare Jonio. Blocked and seized. Bye bye,” Salvini wrote on Twitter.

Italy’s government has repeatedly accused rescuers of being complicit with people smugglers, who charge large sums to help migrants get to Europe, and Salvini has closed the country’s ports to their boats, most of which have stopped sailing.

UNHCR spokesman Babar Baloch said the UN refugee agency had repeatedly voiced its concerns about the lack of boats to pick up people fleeing from “the horrendous and horrible situation” in Libya.

“It’s really a desperate situation, we have been calling on states to build up search and rescue capacity in the Mediterranean, we have been sharing our concern about not having any boats to rescue these people,” he said.

Asked why the United Nations did not charter a ship to rescue people, he said: “We cannot replace states’ capacity, and states have a responsibility under international maritime law.”

During the Tripoli battle, UNHCR has evacuated 309 refugees to Niger and Italy, and transferred others to a departure facility, now almost full with 617 people, and it hopes to evacuate them on May 23. — Reuters