ROME — More than 100 African migrants who set off in a rickety, inflatable dinghy have died in a wreck off the Libyan coast, humanitarian workers said on Saturday, in what was the deadliest such episode in recent months.

The scale of the catastrophe became clear after three survivors, two Sudanese and one Gambian, who were rescued by the Italian Navy and brought to shore in the southern Italian island of Lampedusa, told the aid workers that 117 migrants had died.

“Survivors told us that they had about 10 women on board, and one of them was pregnant,” Flavio Di Giacomo, a spokesman for the International Organization for Migration, said in a phone interview. “There were also two toddlers, one of them was 2 months old.”

The migrants were believed to have been from countries in West Africa and Sudan. Libya is the principal springboard for most African migrants seeking to enter Europe, and before they even set to sea, the migrants face other dangers like traffickers and violence.

The dinghy set out on Thursday from the coastal town of Garabulli, Libya, west of Tripoli, and in about 10 hours started deflating and taking on water, survivors told humanitarian workers.

When an aircraft from the Italian Navy on a security and surveillance mission spotted the craft 50 nautical miles northeast of the Libyan capital, the vessel had already started sinking, the Navy said in a statement, and roughly 20 people could be seen on board.

The rescue effort comes in a fraught political environment, with several European governments questioning the motives and behavior of independent rescue groups, and some bringing criminal charges against them.

The Italian Navy said that, after launching two inflatable rafts toward the migrants, it immediately called another helicopter to provide support, as their closest vessel was well beyond 110 nautical miles from the shipwreck.

The helicopter rescued the only three survivors and brought them to the hospital on the island of Lampedusa. They were suffering from hypothermia, had burn scars and were traumatized, humanitarian workers said.

The Italian Coast Guard said in a statement that it had “immediately verified that the Libyan Coast Guard was aware of the event within their search and rescue area, ensuring the outmost collaboration.”

It also confirmed that a nongovernmental organization, Sea Watch, had offered its help and that the message was passed on to the Libyan Coast Guard.

In a separate incident,Sea Watch said that it had rescued another 47 people on a rubber dinghy in the Mediterranean on Saturday. But it had yet to receive information on what port, if any, the group could be brought to. One of the group’s boats was stranded at sea for weeks earlier this month after being denied entry to several European ports.

In February 2017, the bodies of 74 migrants were recovered from a beach near the town of Zawiya in western Libya. The bodies were believed to have come from a shipwrecked inflatable raft that was found on the shore.

European countries have struggled to stem the flow of migrants, training the Libyan Coast Guard and offering money and other resources to Libyan officials to shift the migration crisis off its shores and to deal with it at the source. But the migrants keep making the perilous journey.

On Friday night, the Italian Navy said the rescue operations, coordinated by the Libyan Rescue Coordination Center, had concluded after the search for the dinghy proved fruitless.