A court has imposed heavy prison terms on three people convicted of human trafficking from Libya, a key North African departure point for migrants seeking a better life in Europe.

The attorney general's office said in a statement on Friday that one of the three, whose identities and nationalities were not given, was sentenced to life in prison and the other two to 20 years each.

They are the first convictions in Libya in human trafficking cases.

The court found the three guilty of "trafficking in human beings" and having "detained and tortured" illegal migrants and extorted their relatives to pay ransoms to free them, the statement said.

War-torn Libya is regularly criticised for its handling of migrants, with rights groups alleging horrific treatment by smuggling gangs and inside state-run detention centres.

Libya is a key launchpad for migrants who are often fleeing conflict and poverty in sub-Saharan Africa. They aim to reach Italian shores just 290 kilometres (180 miles) to the north across the Mediterranean Sea.

The route is the world's deadliest migratory sea crossing. Libya was plunged into years of chaos after a NATO-backed uprising toppled and killed strongman Moamer Kadhafi in 2011, helping to turn the country into a fertile ground for human trafficking.

In a March report, a United Nations fact-finding mission on human rights in Libya found that some migrants trapped there had been subject to sexual slavery -- a crime against humanity.

In October 2021, the United States and the UN imposed sanctions on a Libyan, Osama Al Kuni Ibrahim, accused of abusing African migrants at a detention centre in Libya.