An appeals court in Iran has sentenced a civil rights activist to six years in jail for signing a letter last year asking Supreme Leader Ali Khamenei to step down, human rights groups reported March 10.

Reza Mehregan is one of the fourteen signatories to the letter published last June and all signatories have been targeted by law enforcement.

Earlier in January, an Islamic Revolution Court sentenced Mehregan to five years for "assembly and collusion against national security," one year for "disturbing public order," and one-year prison and 74 lashes as "supplementary punishment."

Furthermore, the court sentenced the civil rights activist to two years forced exile in the province of Southern Khorasan, northeast Iran.

The signatories to the letter had called for Khamenei's resignation and fundamental change in the Islamic Republic's constitution.

In a statement addressed to the "thoughtful, intellectual, and considerate people of Iran," the signatories had urged their compatriots to leave any "tendency toward discreetness" aside, audaciously step in and demand Khamenei's resignation and fundamentally amending the country's constitution.

"Herald a new national movement," the activists encouraged the Iranian people in their letter, "by demanding Khamenei's resignation", since he is continuously increasing his "unfair" power and authority, they said.

All the signatories to the letter were arrested last August by Intelligence Ministry agents when they gathered in Mashhad in northeast Iran to support Kamal Jafari-Yazdi, also a signatory of the message, who was sentenced to thirteen years in prison for "insulting the leader."

Days after the letter was published, fourteen prominent Iranian women followed suit and signed a similar statement, calling on the 80-year-old Supreme Leader to step down.