An Afghan appeals court has quashed death sentences imposed on four men for their part in the mob killing of a young woman in Kabul in March.

Farkhunda Malikzada was attacked at an Islamic shrine after being falsely accused of burning a copy of the Koran.

She was stoned to death; her body was run over by a car and set on fire.

The court also acquitted the keeper of the shrine. Family members and rights activists have expressed outrage at the decision, which was taken in secret.

Wednesday's appeal court hearing in Kabul was held behind closed doors - local media report that the four death sentences were commuted to 20-year jail terms.

The brutal killing shocked the world and has been seen as a potential watershed in Afghanistan. Photo taken from BBC.

The decision also reportedly acquits Omran, the keeper of the shrine, who was the one to incite the mob to kill Malikzada, 27, after she had argued with him.

Malikzada's brother Najibullah told BBC Persian: "It's not a court, it's just a show... The media should have been there, we should been there, the lawyers should have been there.

"It's a real theatre. The whole world laughs at the judicial system of Afghanistan. Do the judges have families, sisters, mothers - or not? Do they have a heart? We will not accept this decision."

He accused the authorities of "a tyranny" against the family, who have been living in fear since the attack.

At the original trail in May, eight men were given jail terms of 16 years, as well as the four who received death sentences.

Later in the month, 11 policemen were sentenced to one year in prison for failing to protect Malikzada, a devout Islamic student. Eight other police officers were acquitted.

The treatment of the police was condemned as too lenient, in a country where women are frequently denied justice.

Kimberley Motley, an American lawyer in Afghanistan who represented the family during the previous trial, also criticised the ruling.

"I'm extremely surprised and disappointed. I'm very concerned because this happened in a much closed hearing, it wasn't transparent as the first court was and so there are questions as to why this even occurred.

"There's very strong evidence through video and through eyewitness testimony that justified the original sentences that were imposed on these men."