KABUL: An appeals court in Afghanistan's capital has set aside death sentences for four men convicted in the mob killing of a woman accused of burning a Koran, media and a judge said Thursday.

Three of those had their sentences reduced to 20 years in jail, while the fourth was re-sentenced to 10 years, according to a judge familiar with the case that prompted street protests and a debate on women's rights.

They were originally sentenced in a May trial for leading a crowd of people who beat and kicked the woman, named Farkhunda, and set her body on fire in central Kabul as bystanders chanted "God is great".

Their convictions were based in part on mobile phone footage of the March attack that was played in court.

The deadly attack proved a polarizing incident in Afghanistan, a deeply conservative Muslim country. Initially, some clerics said the killing was a defence of Islam.

Many others were outraged by the attack, even before an investigation showed that Farkhunda had been falsely accused of desecrating Islam's holy book.

Some of those arrested were tracked down after posting footage of the attack on social media and bragging about taking part.

Tolo TV station first reported the sentence reductions on Wednesday, quoting anonymous sources.

A judge familiar with the case confirmed the story.

"I confirm that the decision was reversed because the defence prosecutor was not satisfied," said the Kabul judge, speaking on condition of anonymity because he was not presiding over the case.

He added that the case would now go to another appellate court that could again change the sentences.