Saif al-Islam Gaddafi, the son of deposed Libyan leader Muammar Gaddafi, has been freed by an armed group holding him in the western town of Zintan where he was taken after the 2011 revolt against his father, according to one of his lawyers and a statement from the brigade.

In a statement on Sunday, the Abu Bakr al-Seddiq Brigade, which controls Zintan, said Gaddafi's son had been released from prison on Friday and left the town.

The statement said Saif al-Islam had been freed under an amnesty promulgated by the East Libya-based parliament.

There was no comment from the Tripoli-based national unity government on the claim.

The lawyer, Khaled al-Zaidi, said Saif al-Islam was headed to another Libyan city, but he could not say where for security reasons.

During Gaddafi's rule, Saif al-Islam had been his heir apparent. When the uprising against Gaddafi broke out in 2011, he returned to Tripoli to support his father.

After Gaddafi was killed in August of 2011, Saif al-Islam was captured in the Sahara Desert while trying to flee to Niger.

In 2014, he was put on trial for war crimes and sentenced to death, but human rights groups and the UN said there was a lack of due process at his trial.

Since Gaddafi's departure, Libya has remained in a state of turmoil with the country's stark political divisions yielding at least three different seats of government and a host of rival militia groups.