Clashes have erupted between Iranian security forces and a crowd marking the 40th day of mourning for a young woman shot dead while protesting near Tehran.

Authorities shut a cemetery to stop thousands of people reaching the grave of Hadis Najafi, who has become a symbol of the unrest engulfing Iran.

Videos showed protesters blocking a highway in Karaj, burning a vehicle and shouting anti-government slogans. Security personnel were seen firing tear gas towards them in other footage.

Hadis Najafi, a 22-year-old TikToker, recorded a video on her phone as she walked to a demonstration in Karaj, just west of Tehran, on 21 September.

"I hope in a few years when I look back, I will be happy that everything has changed for the better," she says, as night falls around her, in the video obtained by BBC Persian.

Her family said that she was shot dead by security forces almost an hour later. Officials allegedly asked her father to say that she died of a heart attack.

Norway-based Iran Human Rights said on Wednesday that 277 people, including 40 children and 24 women, had been killed by security forces in a violent crackdown

Authorities have denied involvement in the killing of protesters, instead blaming foreign-backed "infiltrators" and "terrorists".

Today is 40 days since the death of another young woman, #HadisNajafi. The authorities have tried to stop mourners from going to her grave, so mourners have blocked the road.