Iran's Supreme Leader blames 'enemies' for protests, death toll hits 21

In his first remarks since the demonstrations erupted last Thursday, Khamenei accused the nation's enemies of "joining forces" against Iran and blamed them for the violence in recent days.

"The enemy is waiting for an opportunity, for a flaw, through which they can enter. Look at these events over the last few days. All those who are against the Islamic Republic, those who have money, those who have the politics, those who have the weapons, those who have the intelligence, they have all joined forces in order to create problems for the Islamic Republic and the Islamic Revolution," he said.

"God willing I have got things to say to my dear people in due course. The animosity is there, but what can prevent this animosity is the spirit of bravery, the spirit of sacrifice and the spirit of faith, a good example of which was your children."

Khamenei did not make clear exactly who he was referring to, but Iranian President Hassan Rouhani earlier slammed US President Donald Trump for tweeting his support for the protesters.

Trump wrote on Monday: "The great Iranian people have been repressed for many years. They are hungry for food & for freedom. Along with human rights, the wealth of Iran is being looted. TIME FOR CHANGE!"

Other Iranian officials had blamed "foreign agents" and an online "proxy war" waged by the US, the UK and Saudi Arabia for the violence.

Khamenei's remarks followed more deadly violence on Monday, in which nine people were killed, including seven protesters, a member of a pro-government militia and a policeman. Twelve others were killed over the weekend as the protests intensified.

The protests have become the biggest challenge to the government's authority since mass demonstrations in 2009. Around 450 people have been arrested over the past three days, according to state media.

Protesters storm police station, report says

On Monday, six protestors were killed in the central city of Qahdarijan when demonstrators stormed a police station and attempted to take guns from authorities, state media reported.

A member of the Basij, a pro-government militia, was killed in south Tehran. And a policeman in Najafabad was killed when a protester shot at officers with a hunting rifle, according to state media. Three other officers were wounded.

Among the 12 people killed over the weekend were a man and his young son, when a fire truck hijacked by protesters ran them down on a street in western Iran's Dorud, according to the semi-official ISNA news agency.

Video images shared on social media from central Tuyserkan on Sunday showed protesters throwing chairs, tables and other objects in reach at riot police, forcing the outnumbered officers to retreat. Six protesters were shot dead in the unrest there, according to the semi-official Fars news agency.

The rallies began Thursday over the country's stagnant economy and rising living costs, but they developed into a broader outcry against the government and intensified over the weekend.

Iranian President Hassan Rouhani tried to downplay the significance of the protests, which have spread beyond the capital of Tehran to at least 18 cities.

"Our great nation has witnessed a number of similar incidents in the past and has comfortably dealt with them. This is nothing," Rouhani said in a meeting with Iranian members of parliament Monday.

But other officials have warned of strict crackdowns, and the mass arrests show that the country is concerned by spreading dissent.

Ali Asghar Nasser-Bakht, Tehran's Deputy Governor for Political and Security affairs, warned that "those who wish to congregate in public must obtain permits from the Ministry of the Interior, and be aware than any public disturbances or threats, are against the laws and they will not be tolerated."