Iranian dissident journalist Keyvan Samimi, imprisoned since December 2020, was released on Thursday, his family told AFP.

Samimi, 74, had been sentenced to three years in prison for "plotting against national security".

"Samimi, who had been transferred last year to Semnan prison", located nearly 200 kilometres (125 miles) east of Tehran, "was released this afternoon", his family said.

The journalist had been granted permission to leave prison on medical grounds in February 2022.

But he returned to prison in May after being suspected of carrying out activities against national security, Iran's Mehr news agency said.

In December, Samimi sent a message from his cell in support of the protest movement that has shaken Iran since the September 16 death of Mahsa Amini.

The 22-year-old Iranian Kurd died in the custody of the morality police in Tehran after her arrest for an alleged breach of the Islamic republic's dress code for women.

Samimi has spent time behind bars before and after the 1979 Islamic Revolution.