Farkhunda, the Afghan woman who was beaten to death by a mob, has been buried with women's rights activists carrying the coffin.

Hundreds of people attended the funeral of the 27-year-old who was lynched after her attackers accused her of burning the Koran.

Footage of the attack, filmed on mobile phones, has been widely circulated on social media.

The police have been accused of "looking on" as the woman was attacked, according to the BBC.

Afghanistan's President Ashraf Ghani said he had ordered an investigation into the killing.

An interior ministry official in charge of investigating the case said he had found no evidence that Farkhunda had burnt 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. "Farkhunda was totally innocent."

Zahir confirmed that 13 people, including eight police officers, had been arrested.

Hundreds of people attended her funeral chanting "we want justice" and her coffin was carried by women – a role traditionally performed by men.

Earlier claims that Farkhunda was mentally ill have been disputed by relatives and a neighbour.

Speaking to Reuters, Farkhunda's brother, Najibullah, confirmed that his sister was training to be a religious teacher. He went on to say that her father had said she was ill after hearing of her death because he wanted to protect the rest of the family.

An interior ministry spokesperson said that Farkhunda's family was staying in protective care.

Afghanistan is described as one of the world's worst places to be a woman by international rights groups.

Western countries and organisations have spent millions of dollars on programmes designed to empower and educate Afghan women. Progress has been made, however, women in much of the country still suffer discrimination and attacks on them are carried out with impunity.

Earlier this month, an Afghan woman was nearly lynched after walking through the streets of Kabul wearing metal armour in a bid to denounce sexual harassment.