The 70-year-old mother of a blogger who was allegedly tortured and died in prison in 2012 has accused Iran's state television of faking a video to discredit her.

In a video posted to social media last week, Gohar Eshghi said she was pushed over steel bars on the side of a street by two motorcyclists as she was going to her son's grave. With large bruises under her eyes and a bandaged forehead, Eshghi said one of the motorcyclists dismounted, pushed her, and she passed out: "When I came to, I was in hospital."

A week later, on December 16, Iranian state television aired a video, which it said was from close-circuit cameras (CCTV), showing a woman resembling Eshghi from behind, swaying, staggering, and falling over the steel bars. No motorcyclists were in sight, but passers-by rushed to help, and called an ambulance.

The television program, 20:30, also interviewed the ambulance driver, and witnesses who said they saw Eshghi faint and fall.

"They are lying,” Eshghi told New York-based rights activist Masih Alinejad on Instagram following the TV program. “Why didn't they [show footage] from these cameras the first day? Why didn't they check their security cameras when my Sattar was killed to find my son's murderer?"

Some posts on social media claim the quality of the images suggests they were taken by “a professional camera” and not CCTV.

Eshghi, who holds Iran’s Supreme Leader Ali Khamenei responsible for her son Sattar’s death, has set up a foundation in her son's memory that she says she had been under pressure to shut down. She was detained for five days in June.

Eshghi's 35-year-old son, Sattar Beheshti, a laborer, was arrested by police in 2012 due to his blog, My Life for My Iran, and social media posts. Beheshti's last blog post published a day before his arrest was a critical letter addressed to Supreme Leader Ali Khamenei in which he called Iran's Judiciary "a slaughterhouse" that aimed to terrorize the Iranian people into submission and silence. He also claimed he had been threatened by “intelligence bodies”to shut his “big mouth.”

Charged with security offences, he died in detention a few days after his arrest, and after he had submitted a signed complaint that he had been tortured.

A postmortem identified the cause of his death as internal bleeding. Beheshti was buried by security forces in his hometown of Robat Karim, about 30 km from Tehran. Authorities denied allegations of torture and attributed his death to "natural causes", but 41 political prisoners at Evin prison signed a letter claiming his injuries had resulted from “hanging from the ceiling and severe beating.”