Prominent Azerbaijan's human rights activist Leyla Yunus has been released from custody due to her worsening health condition. The 59-year-old campaigner, who had been sentenced to eight-and-a-half years in prison for fraud and tax evasion, has diabetes and hepatitis C.

Yunus had worked for the Peace and Democracy Institute in Baku with her husband, Arif, who had been arrested in the capital Baku on the same charges. Both documented the treatment of political prisoners in Azerbaijan by authorities under the iron first of President Ilham Aliyev, who has suppressed political opposition since he came to power in 2003.

Arif is also in bad health and has suffered two strokes. He was released in November. Groups such as US-based Human Rights Watch condemned their persecution as a "despicable political show trial". Amnesty International called Leyla and Arif Yunus "prisoners of conscience".

"The judicial system has once again revealed itself to be no more than a cynical tool by which President Ilham Aliyev crushes any dissent or criticism of his regime. His government's human rights record is simply shocking," Levan Asatiani, campaigner at Amnesty International, said at the time.

Leyla was arrested on 30 July 2014 after organising a press conference calling for an international boycott of the European Games because of Azerbaijan's dire human rights record. Rights activists in the oil-rich country and abroad believe charges against human rights activists are often fabricated in retaliation for their work and criticism of the regime.

The Institute for Peace and Democracy has worked with the Council of Europe, the bloc's leading human rights watchdog informing them about actions to crack down on political dissident in Azerbaijan. The couple both still face charges of treason and their legal situation remains unchanged, despite being released.