Late Libyan dictator Muammar Gaddafi's son, Saif Al-Islam Gaddafi has been released after six years in detention by a militia group in the city of Zintan.

In a statement to the media, the militia group Abu Bakr al-Siddiq on Saturday night said that Saif al-Islam Gaddafi, had been released on Friday and that he immediately left Zintan where he was captured in November 2011, a month after his father was killed in the city of Sirte, reports Efe news.

"We decided to release Saif al-Islam Gaddafi. He is now completely free. We confirm that he abandoned Zintan at the time of his release," the group said.

Hours later, the online daily Libyan Express said Saif, who faces an arrest order issued by the International Criminal Court (ICC), was taken to the eastern city of al-Bayda, reports Efe news.

"Saif is now among his uncles and relatives in al-Bayda and will soon deliver a speech to the Libyan people," the daily said.

The ICC accuses Saif of crimes against humanity, saying he ordered the killing and torture of Libyans during the 2011 rebel uprising that overthrew his father.

On the basis of those accusations, a court in Tripoli in 2015 convicted Saif in absentia and sentenced him to death. The trial, however, has been criticised for alleged irregularities.

His captors, however, refused to turn him over to the different authorities in the Libyan capital or to the international tribunal.

Since last July, he had been under a regime of semi-liberty — under the control of the militias in Zintan but free to receive visitors.

Libya remains politically divided after six years of conflicts with two competing parliaments and governments, one based in Tripoli and the other in the eastern port city of Tobruk.

With mediation efforts of the international community, political rivals signed a UN-sponsored peace agreement in December 2015 which led to the establishment of the Government of National Accord (GNA) headed by Prime Minister Fayez al-Sarraj and based in Tripoli.

However, the Tobruk-based parliament, which is recognised by the international community, has refused to endorse the government.