Images appeared online of unveiled women competing in the race on Friday.
Iranian officials are encouraging people to report women who refuse to obey the Islamic republic's dress code, according to a UN report.
It comes as the UN warns Iranian women still face violent punishment for not wearing the hijab.
Women tell how their posts are being spied on, two years after Mahsa Amini's death rocked Iran.
Narges Mohammadi, 52, speaks out in a message from Evin prison where she is being held.
Revolutionary Guards' papers passed to the BBC give chilling details of Nika Shakarami’s last movements.
The UN mission also found "disproportionate use of lethal force" by security forces against protesters.
Unofficial reports suggest the turnout for Friday's national poll was the lowest since the 1979 revolution.
Three women describe how they flout headscarf laws ahead of the first polls since nationwide protests.
