One of the world's longest-serving political prisoners has been released in Uzbekistan, where he was held for 21 years.

The release of Murod Juraev on Thursday was announced by international human rights groups, which have long raised concerns about his imprisonment and allegations that he was tortured.

Government agencies in the Central Asian country did not immediately respond to requests for confirmation.

Nadezhda Ataeva, who heads the Association for Human Rights in Central Asia, told The Associated Press on Friday that Juraev was already home and with his family.

Juraev was a member of parliament in the years immediately following the Soviet breakup. He was also the mayor of a southern town and a prominent member of an opposition party.

The U.S. State Department issued a statement welcoming his release.