Haidar al-Zaidi, 20, was sentenced to three years over a tweet of disputed origin deemed insulting to a pro-Iran paramilitary force, according to court documents seen by AFP Wednesday.

The verdict, which Zaidi can appeal, has sparked criticism on social media.

Hundreds of people gathered for a second day in a row on Wednesday evening in central Nasiriyah, the regional capital of Dhi Qar province, to condemn the sentencing and also to demand compensation for people wounded by security forces in protests in late 2019.

The protesters chanted anti-government slogans, according to an AFP correspondent.

"Two protesters were shot dead" in the clashes and 21 others were wounded, including five by gunfire, said Hussein Riyad, a spokesman for the Dhi Qar provincial health ministry.

Riyad said a police officer was among those wounded.

Zaidi was sentenced on Monday in the capital Baghdad over a post, long since deleted from his Twitter account, criticising the slain deputy commander of the former paramilitary Hashed al-Shaabi force, Abu Mahdi al-Muhandis.

The activist wrote on Facebook on Sunday that he faced charges of "insulting state institutions".

New York-based advocacy group Human Rights Watch (HRW) called for Zaidi's immediate release and urged Iraqi authorities not to use the courts as a "tool to suppress peaceful criticism".

Muhandis was killed in a US drone strike in Baghdad in January 2020 alongside Iranian foreign operations commander General Qasem Soleimani.

He is revered as a martyr by the Hashed, a paramilitary group integrated into Iraq's security forces and whose political wing forms part of Iraq's ruling coalition.

Zaidi has denied he posted the tweet, claiming his account was hacked, according to HRW.

"Regardless of who posted the Twitter message, the Iraqi justice system should not be used as a tool to suppress peaceful criticism of the authorities or armed actors," said HRW's deputy Middle East director, Adam Coogle.

Nasiriyah was a bastion of a wave of anti-government protests that hit Iraq in late 2019 and were crushed by authorities in a bloody crackdown that killed more than 600 people.

The impoverished city has since seen rallies by young people demanding access to jobs in the public sector.