Media playback is unsupported on your device Media caption Farkhunda was speaking for a more orthodox Islam, David Loyn reports (Report from March 2015)

An Afghan woman who was lynched after being falsely accused of burning the Koran was killed for tackling superstitious practices, witnesses say.

Farkhunda, who was beaten to death by a Kabul mob last week, had been arguing with a mullah about his practice of selling charms to women at a shrine.

In the course of the argument she was accused of burning the Koran and a crowd overheard and beat her to death.

Hundreds of Afghans protested on Monday against the attack.

At the scene: David Loyn, BBC News, Kabul

Image copyright EPA

The event has raised new questions about the pace of reform in Afghanistan. And there has been no attempt in the government to deny the seriousness of what happened. A spokesman for the interior ministry, Sediq Sediqi, said the father was right to say that the police could have done more to save Farkhunda. "We will have to work on our measures, on our teaching and training for our police across the country, and this incident will bring a lot of changes within us," he said.

Farkhunda, 28, was beaten, hit by bats, stamped on, driven over, and her body dragged by a car before being set on fire.

A policeman who witnessed the incident on Thursday told AP news agency that Farkhunda was arguing with a local mullah. Her father said she had complained about women being encouraged to waste money on the amulets peddled by the mullahs at the shrine.

"Based on their lies, people decided Farkhunda was not a Muslim and beat her to death," Mohammed Nadir told AP.

The policeman who saw the incident, Sayed Habid Shah, said Farkhunda had denied setting the Koran on fire.

"She said I am a Muslim and Muslims do not burn the Koran," he said. "As more people gathered, the police were trying to push them away, but it got out of control," he added.

Image caption The killing has triggered unprecedented public outrage

Image copyright AFP Image caption Protesters demanded that the government prosecute all those responsible for her death

An official investigator has also said there was no evidence she had burned the Koran.

"Last night I went through all documents and evidence once again, but I couldn't find any evidence to say Farkhunda burnt the Holy Koran," General Mohammad Zahir told reporters at her funeral on Sunday. "Farkhunda was totally innocent."

Police say they have detained 18 people over the incident, with more arrests expected. In addition, 13 policemen have been suspended for having failed to do enough to stop the attack.

Shukria, a woman visiting the shrine on Monday, told the BBC that the attack was "not just an attack on Farkhunda, but on all Afghan women. They have killed us all".

Demonstrators have called for justice and planted a commemorative tree.

Image caption Children joined the march

Image copyright Reuters Image caption Farkhunda, 27, is reported to have been a religious scholar

Afghan President Ashraf Ghani has ordered an investigation into her death.

The attack, near the Shah-Du-Shamshaira mosque and shrine, is thought to have been the first of its kind in Afghanistan.

Breaking with tradition, women's rights activists carried the coffin at her funeral, a role usually performed by men.

Farkhunda's family initially claimed she was mentally ill, but this has since been retracted by her father who said he was told to say so by police to reduce the chances of violent reprisals against them.