Security forces in Iran used tear gas to disperse protesters who had gathered at the Tehran Grand Bazaar in the Islamic Republic's capital on Tuesday, according to witnesses and rights groups.

According to reports, demonstrators had been holding a sit-in at the Grand Bazaar and had been chanting slogans against clerical authorities.

Rights groups share footage of bazaar protest

Social media footage verified by French news agency AFP showed protesters at the scene shouting slogans including "Pahlavi will return" and "Seyyed Ali will be overthrown" — in references to the monarchy ousted during the 1979 Islamic Revolution and to Supreme Leader Ayatollah Ali Khamenei.

In footage posted by the Norway-based group Iran Human Rights and US-based Human Rights Activists News Agency, demonstrators shouted "freedom" and "shameless."

Security forces could then be seen firing tear gas at those gathered, who then rushed to get away from smoke.

Violence surrounding the protests — triggered by rising cost of living — has claimed at least 12 lives, according to official figures carried by Iranian media.

Foreign-based Iranian activists say at least 27 protesters have been killed and more than 1,000 people have been detained.

The figures cannot be independently verified.

On Sunday, US President Donald Trump warned that the regime would get "hit very hard" by the US if more protesters died.

What has led to the protests?

Protests erupted after a currency collapse following UN sanctions, with $1 (€0.86) now worth about 1.4 million rials.

The prices of staples such as meat and rice have risen dramatically as Iran has been battling a spiraling inflation rate of some 40%.

Demonstrations have widened into demands for broad change, and have spread nationwide.

In response to economic pressure, the government announced a temporary monthly allowance equivalent to about $7 for four months.

Edited by: Wesley Dockery