At least two people have been killed as anti-government protests in Iran entered the third day with Iranians chanting slogans like "death to Khamenei". In what has been described as one of the biggest demonstrations in several years, people have been gathering in large numbers in several Iranian cities despite stern warnings from the regime.

The protests began over the failing economy and falling standards of living, but are gradually spiralling into a larger anti-government campaign with people demanding an end to alleged corruption. Rallies first started in Iran's second-largest city of Mashhad on Thursday (28 December) and then spread to other major cities including Tehran. This is said to be the largest show of dissent against the theocratic regime since 2009 when months of upheaval rocked the country after a contested presidential election which catapulted Mahmoud Ahmadinejad to the presidency.

According to unconfirmed reports, three people were killed in the city of Doroud when Iranian security forces opened fire on protesters. Interior Minister Abdolrahman Rahmani Fazli had earlier called on Iranians not to participate in the "illegal gatherings" warning of strong action against those defying the diktat.

Videos shared by the People's Mojahedin Organization of Iran (PMOI/MEK), an anti-Iran group which champions armed overthrow of the Iranian government, with IBTimes UK show there were fierce clashes in many Iranian cities. The videos could not be independently verified.

"Without a doubt, this unjust bloodletting will double the anger of the people against the clerical regime, further inflame the fire of uprising, and accelerate its overthrow," Shahin Gobadi, a spokesperson for the radical organisation, said in a statement sent to IBTimes UK.

Riot police have sporadically used tear gas in order to quell the protests. Some protesters were heard chanting slogans such as "death to dictator" and "death to Khamenei" in reference to the country's Supreme Leader Ayatollah Ali Khamenei. These are unprecedented in terms of dissent since Khamenei, who wields the highest political authority, is hardly criticised in public. Images of Khamenei have also been brought down by angry protesters.

Meanwhile, the Iranian foreign ministry has hit back at the US for expressing support for the anti-government rallies. Calling Washington's comments as "cheap, worthless and invalid", the ministry's spokesman Bahram Qassemi said: "The great Iranian nation regards the opportunist and duplicitous support of the American officials for certain gatherings over the recent days in some Iranian cities as nothing but [part of] the deceit and hypocrisy of the US administration."