A member of Iran's security forces was killed during a fourth day of protests in the country, which have been sparked by a currency collapse, the semi-official Fars news agency has reported.

Citing regional official Said Pourali, Fars said the incident happened in the city of Kouhdasht, in the western Lorestan province, adding that a number of members of the security forces were also injured.

Footage verified by BBC Persian appears to show security forces firing at protesters in the city on the same day.

Confrontations were also reported in the southern province of Fars and the western provinces of Hamedan and Lorestan on Thursday.

The authorities in the capital, Tehran, had declared Wednesday a bank holiday - in an apparent effort to quell the unrest, which started in the capital on Sunday.

The Fars report said a 21-year-old member of the Basij - a paramilitary force linked to Iran's Revolutionary Guards - was killed during a confrontation in the city of Kouhdasht. Thirteen police officers and Basij members had been injured by stone throwing, the report said.

Unrest broke out in other cities too. In the southern province of Fars, protesters tried to break into a local government building, with officials reporting three police officers injured and four people arrested in the city of Fasa.

In video that emerged on social media and verified by the BBC, a crowd is filmed breaking the gate of the governor's office in the city. Then, in another post, security men are seen shooting in response. Clouds of tear gas rise in front of shuttered shops.

Across the country, schools, universities and public institutions were closed because of the last-minute public holiday announced by the Iranian government. It was ostensibly to save energy because of the cold weather, though it was seen by many Iranians as an attempt to contain the protests.

They began in Tehran - among shopkeepers angered by another sharp fall in the value of the Iranian currency against the US dollar on the open market. By Tuesday, university students were involved and they had spread to several cities, with people chanting against the country's clerical rulers.

The protests have been the most widespread since an uprising in 2022 sparked by the death in custody of Mahsa Amini, a young woman who was accused by morality police of not wearing her veil properly. But they have not been on the same scale.

To prevent any escalation, tight security is now reported in the areas of Tehran where the demonstrations began.

President Masoud Pezeshkian has said his government will listen to the legitimate demands of the protesters. But the prosecutor general, Mohammad Movahedi-Azad, has also warned that any attempt to create instability would be met with what he called a decisive response.