Eritrean migrants are rescued by a boat operated by the aid group Proactiva Open Arms in the Mediterranean Sea near Libya in April. (Bernat Armangue/Associated Press)

MILAN — The central Mediterranean is one of the world’s deadliest migration routes: Last year, 4,576 migrants lost their lives trying to reach Italy from Libya, and more than 2,200 have drowned in the first half of 2017, according to the United Nations’ International Organization for Migration.

In attempt to cut down on the such deaths, Doctors Without Borders — the Nobel Peace Prize-winning relief organization often known by its French initials, MSF — has patrolled the waters for more than two years, saving 69,000 lives. But on Saturday, MSF announced it would stop operating in the area.

The suspension, said Loris De Filippi, president of MSF’s Italian chapter, was due to “very credible threats” against rescue boats by the Libyan coast guard. But the Italian government, he added, is doing its part to make rescue work nearly impossible by imposing new restrictions and requirements on aid groups operating there.

Charities have been steadily patrolling the central Mediterranean since early 2015, filling the void left when Mare Nostrum, Italy’s military search and rescue mission, was canceled in 2014 because it was too expensive. At first, the Italian government was happy that other groups were taking up the physical and economic burden. But when arrivals of migrants by sea surged in 2016, the government grew concerned that rescue missions were encouraging immigration. Over the past few months, it has started cracking down on groups that rescue migrants.

The Italian government “has done everything in its power to create unfavorable conditions for NGOs like ours,” De Filippi told The Washington Post in a telephone interview.

In July, the tough-on-immigration interior minister, Marco Minniti, threatened to prevent them from docking in Italian ports. In early August, Italian police confiscated the ship of the German charity Jugend Rettet, accusing the group of aiding illegal immigration. Charges have also been filed against a priest for helping the organization.

Last week, the government asked rescuers to sign a controversial “code of conduct” requiring them to have police officers on board, to keep far away from Libyan waters (in an unspecified area well beyond the country’s maritime borders) and to avoid transferring rescued migrants from one boat to another. Most NGOs, including MSF, refused to sign the document, claiming it conflicts with their mission and with international maritime law.

A major problem, said De Filippi, is that “in order to maintain neutrality,” humanitarian ships cannot have armed police personnel aboard. An even bigger issue, he said, is that forbidding the transfer of rescued people from one ship to another will make rescue missions less effective, because it will force a ship to go back to the mainland as soon as it rescues a few migrants. MSF’s current practice is for its ships to transfer rescued migrants to other vessels that are already almost full or heading toward the mainland, allowing the group to keep more ships free to patrol.

“This code of conduct is all about making NGO ships less effective,” said Matteo de Bellis, a migration researcher at Amnesty International. “It’s the result of a wrong belief that having rescuers attracts migration.”

Gianfranco Schiavone, the vice president of ASGI, an immigration law research institute, agreed that the code of conduct “is specifically designed to hinder the work of humanitarian ships.” But he argued that it “has no legal value whatsoever” because it conflicts with international law, which mandates that rescue operations be carried out in the most quick and effective ways possible.

However, another legal expert — Fulvio Vassallo Paleologo of the University of Palermo — warned that the code could carry “serious consequences” for rescuers because it could expose them to accusations of aiding illegal immigration. “It’s a trick to make NGOs more vulnerable to future legal actions,” he said.

Italy’s Interior Ministry declined to comment, and the prime minister’s office did not respond to requests for comment.

Analysts say the government’s new policies on rescue operations are part of a wider plan to reduce sea arrivals from Africa, which includes controversial cooperation with Libyan authorities.

“They’re just trying to keep NGOs as far away from Libya so that the Libyans could do whatever they want with no witnesses around,” De Filippi said. And so far, it seems, they’re succeeding: As Italy heads toward elections in early 2018, Prime Minister Paolo Gentiloni is boasting that his tough approach has lead to a drop in sea arrivals.