The United Nations said the European Union is partly responsible for the deaths of migrants taking boats across the Mediterranean due to unanswered distress calls, obstruction of humanitarian rescue efforts, and pushbacks.

Thousands of refugees and migrants including many from Africa undertake long, dangerous journeys via Libya to Europe each year, often embarking on small, inflatable boats in search of a better life.

Death rates are rising and so far this year at least 632 people have died on that route, the U.N. rights office said in a 37-page report entitled “Lethal Disregard,” calling this a “human tragedy on a massive scale.”

The report found that the lack of migrant protection “is not a tragic anomaly, but rather a consequence of concrete policy decisions and practices by the Libyan authorities, European Union member states and institutions, and other actors…”

The EU has not only cut back on its own official search and rescue operations but individual governments have prevented humanitarian agencies from rescuing migrants in distress, by impounding their vessels and targeting individuals with administrative and criminal proceedings, the report said.

There have also been “pushbacks at sea” where migrant vessels have been returned from international waters to Libya with the help of European helicopters, migrants told the U.N. rights office.

The report, covering the period from January 2019 to December 2020 and based on interviews with 80 migrants, also said some interceptions by Libyan authorities had endangered migrants. Some boats were rammed or shot at, causing boats to capsize or migrants to jump overboard. Often, migrants face exploitation and abuse back in Libya.

Commenting on the report, U.N. High Commissioner for Human Rights Michelle Bachelet called for urgent reforms of search and rescue policies and practices in Libya as well as the EU and its member states to ensure compliance with international law.

“The real tragedy is that so much of the suffering and death along the central Mediterranean route is preventable,” she said.

Libya has in recent years emerged as the dominant transit point for migrants fleeing war and poverty in Africa and the Middle East. The oil-rich country plunged into chaos following a NATO-backed uprising that toppled and killed longtime ruler Moammar Gadhafi in 2011.

Under a 2019 military and security cooperation agreement between Turkey and Libya, the Turkish Mission Group Command has been providing training and consultancy support to the Libyan military and helping the Libyan coast guard with humanitarian efforts.

In recent years, Libya has become a crucial point for African irregular migrants trying to reach Europe fleeing poverty and conflict in their countries.

Smugglers often pack desperate families into ill-equipped rubber boats that stall and flounder along the perilous Central Mediterranean route. Over the last several years, hundreds of thousands of migrants have reached Europe either on their own or after being rescued at sea.

Thousands have drowned along the way. Others were intercepted and returned to Libya to be left at the mercy of armed groups or confined in squalid detention centers that lack adequate food and water, according to rights groups.