Fresh anti-regime protests took place overnight alongside celebrations for Iran's traditional fire festival in the runup to Persian New Year, monitors said on Wednesday.

Video footage posted on social media showed groups of Iranians chanting anti-regime slogans, throwing headscarves into fires and burning images of the clerical leadership.

The fire festival, called Chaharshanbe Suri in Farsi, is celebrated every year on the night of the last Tuesday of the Iranian calendar year, which ends on March 20.

It is part of Iran's pre-Islamic heritage and generally frowned upon by the Shiite clerical establishment but is popular with young people.

During the festival, participants jump over bonfires to ward off evil spirits. They also let off fireworks, many of them homemade, resulting in significant casualties every year.

Iran's emergency services chief, Jafar Miadfar, said 11 people were killed and more than 3,500 injured during this year's celebrations.

It was the first fire festival since protests erupted in Iran in September over the death in custody of 22-year-old Mahsa Amini, following her arrest for an alleged violation of Iran's mandatory dress code for women.

The 1500tasvir social media channel, which monitors protest activity, posted footage of dozens of people marching in the Tehran district of Ekbatan chanting: "We are back, the uprising continues."

It also posted footage of a large crowd chanting anti-regime slogans in the city of Rasht close to the Caspian Sea coast and of fireworks being thrown at police vehicles in Tehran.

In Tehran, women were shown dancing around bonfires and jubilantly throwing their mandatory headscarves into the flames.

The New York-based Center for Human Rights in Iran said protests also took place in Kurdish-populated regions of western Iran, with people shouting "death to the dictator" in Amini's hometown of Saqez where security forces reportedly used tear gas.

In the town of Bukan farther north, IranWire website said protesters lit bonfires in the streets, prompting clashes with security forces.

In the capital, protesters set fire to a banner of supreme leader Ayatollah Ali Khamenei in the Ekbatan neighbourhood, it added.

The protests that followed Amini's death last September have largely abated in recent months following a deadly crackdown by the security forces.

But analysts have said they need only a spark to flare up again as underlying grievances remain unaddressed.