Defence lawyer Aso Hashem told AFP that "three of the five judges of the cassation court upheld the sentence" passed February 16 by a court in Arbil, capital of the autonomous Kurdish region in northern Iraq.

Former judge and lawmaker Latif Moustafa, who left the Kurdish judicial system over its politicisation, confirmed the ruling.

Journalists Ayaz Karam, Kohidar Zebari and Sherwan Sherwani, along with activists Shivan Saed and Harwian Issa faced multiple charges, including "inciting protests and destabilising" Kurdistan, as well as "spying", "armed" struggle and "misuse of electronic devices".

The five men covered or took part in anti-government protests held last year in several Kurdish cities and towns over a major fiscal crisis that caused delayed public sector salaries and pay cuts.

Human Rights Watch said the charge of "spying" was based in court solely on social media posts and testimony of "secret informants", who did not appear and were not cross-examined.

"These men were sentenced because of a biased political will," charged Belkis Wille, senior researcher at HRW.

A US State Department report last year on human rights in Kurdistan said "senior leaders reportedly influenced politically sensitive cases".

Sherwani, known for his investigations into corruption, had criticised Kurdish prime minister Masrour Barzani on Facebook before his arrest.

The cassation court's decision "represents how significantly Kurdish authorities have allowed free expression to be eroded", Wille added.

On Monday, World Press Freedom Day, journalist Karoukh Othmane was arrested in the Kurdish province of Sulaimaniyah.

Karzan Fadhel, a lawyer and head of the Democracy and Human Rights Development Center in Sulaimaniyah, has listed "74 political prisoners" in Arbil and Dohuk, all "dissidents or protesters indiscriminately arrested on charges of security offences or terrorism".