Rome/Italy — Italy's top appeals court has established that sending sea migrants back to Libya is unlawful, a ruling hailed by charities and human rights groups.

The Court of Cassation upheld the conviction of the captain of an Italian towboat, Asso 28, who in 2018 rescued 101 migrants from a rubber dinghy and returned them to Libya.

The rescue took place in international waters about 105 km off Libya, the court said. Pregnant women and children were among the migrants, it added.

The captain - whose name was blacked out in the ruling for privacy reasons - was sentenced to one year's imprisonment for the crimes of abandoning minors or incapacitated persons, and arbitrary disembarkation and abandonment of persons.

He is unlikely to go to prison, however, as in the Italian system jail terms of under four years are not normally served behind bars.

The ruling is final, upholding earlier decisions by two lower courts.

Italy and other European governments have taken an increasingly hard line on immigration in recent years, amid a swell in support for right-wing parties that want strict curbs on sea arrivals from North Africa. The Libya to Italy crossing is one of the most-used sea migration routes.

"Now there is also a judicial precedent that confirms what we have been saying for years: Libya is not a safe country", the Mediterranea Saving Humans migrant rescue group said on X.

The Italian office of Amnesty International also hailed the verdict, and criticised the government for cooperating with Libyan authorities on migration.