Clashes overnight between protesters and security forces in Iran have left nine people dead, state TV reports said, amid reports around 450 people have been arrested during three days of protest the capital Tehran.
The demonstrations, the largest to strike Iran since its disputed 2009 presidential election, have seen six days of unrest across the country and a death toll of at least 20.
The semi-official ILNA news agency quoted Ali Asghar Nasserbakht, a security deputy governor of Tehran, who said 200 protesters were arrested on Saturday, 150 on Sunday and 100 were arrested Monday.
Offering his first comments since they began, Supreme Leader Ayatollah Ali Khamenei accused the "enemies of Iran" of meddling in the country's affairs.
The protests began on Thursday in Mashhad over Iran's weak economy and a jump in food prices and have expanded to several cities, with some protesters chanting against the government and the supreme leader, Ayatollah Ali Khamenei.
The protests have put pressure on the clerical leaders in power since the 1979 Islamic Revolution.
President Hassan Rouhani has acknowledged the public's anger over the Islamic Republic's flagging economy, though he and others warned that the government wouldn't hesitate to crack down on those it considers lawbreakers.
All the protest rallies so far haven't received prior permission from the Interior Ministry, making them illegal under Iranian law.
In comments posted to his official website, Mr Khamenei appeared to blame foreign nations for at least exacerbating the unrest gripping Iran.
"In the recent days' incidents, enemies of Iran utilised various means — including money, weapon, politics and intelligence apparatuses — to create problems for the Islamic system," he said.
The head of Tehran's Revolutionary Court also reportedly warned Tuesday that arrested protesters could potentially face death penalty cases when they come to trial.
Iran's semi-official Tasnim news agency quoted Mousa Ghazanfarabadi as saying: "Obviously one of their charges can be Moharebeh," or waging war against God, a death penalty offence in Iran.
Donald Trump supported the protesters in a tweet: "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!"
The protests began over Iran's economy, which has improved since the nuclear deal that saw Iran agree to limit its enrichment of uranium in exchange for the end of some international sanctions. Tehran now sells its oil on the global market and has signed deals to purchase tens of billions of dollars' worth of Western aircraft.
However, the improvement has not reached the average Iranian.
Unemployment remains high, and official inflation has crept up to 10 per cent again. A recent increase in egg and poultry prices by as much as 40 per cent, which the government has blamed on a cull over avian flu fears, appears to have been the spark for the economic protests.
