Slideshow ( 4 images )

ROME (Reuters) - Migrant arrivals to Italy by sea fell by a third in 2017 compared to a year earlier, the Interior Ministry said on Sunday, as Libyan authorities helped to slow departures during the second half of the year.

More than 119,000 came to Italy by boat this year after a record 181,000 made the crossing in 2016, the ministry said in a statement. Since July, arrivals have declined by more than two thirds versus a year earlier.

“We were able to govern the flow because we were the first to believe that an agreement with Libya was a turning point,” Interior Minister Marco Minniti said in an interview with Corriere della Sera, commenting on the decline.

In February, Italy signed an agreement with the United Nations-backed government in Tripoli, promising aid, equipment and training in exchange for its help in fighting people smuggling. The deal was endorsed by the European Union.

Since then, armed groups supported by the Tripoli government have forced smugglers in the city of Sabratha - a key hub on the western coast - to stop sending out boats. Italy has also bolstered the Libyan coastguard’s ability to turn back boats.

But rights groups and humanitarian organizations operating rescue ships in the Mediterranean have criticized the policy, saying that it traps migrants in a country where they face appalling treatment, including rape, torture and forced labor.

While criticized by some, the figures are considered good news for the ruling Democratic Party (PD) ahead of a national election in March. More than 600,000 migrants have reached Italy by boat over the past four years, making immigration a hot-button political issue.

More than 20,000 are estimated to have died attempting the crossing to Italy, the International Organization for Migration (IOM) estimates, making it the deadliest border for migrants in the world.

But deaths at sea have declined as well, according to the IOM, with 2,833 this year, down more than 38 percent from 4,581 last year.