An Iranian political activist jailed for his messages on social media has died after spending 50 days on hunger strike, his family says.

Vahid Sayadi Nasiri’s sister, Elaheh, told RFE/RL that the authorities had informed the family that the activist had died in a hospital in the city of Qom on December 12.

She said her brother went on hunger strike to protest against the conditions of his imprisonment and to demand his transfer from a high-security unit of a prison in Qom to Tehran’s Evin prison.

Nasiri was initially arrested in September 2015 and sentenced to eight years in prison for “insulting” Supreme Leader Ayatollah Ali Khamenei and "propaganda against the state," according to the U.S.-based advocacy group Iran Human Rights Monitor.

The charges stemmed from posts he had made on his Facebook page.

Nasiri was released early in March after serving 2 1/2 years in prison, but was arrested again in August, reportedly on similar charges.