A semi-official news agency in Iran is reporting that 450 people have been arrested over three days in Tehran since Saturday.
The ILNA news agency report on Tuesday quoted Ali Asghar Nasserbakht, a security deputy governor of Tehran, offering the figure.
Nasserbakht said that 200 protesters were arrested on Saturday, 150 on Sunday and 100 were arrested yesterday.
The protests began Thursday over economic issues and expanded to several cities. No figure has yet been offered for other cities.
Iranian state television is reporting that nine people have been killed overnight amid nationwide protests and unrest.
The report Tuesday puts the death toll in six days of demonstrations to at least 20 people.
State TV says six rioters were killed during an attack on a police station in the town of Qahdarijan.It reported that clashes were sparked by rioters who tried to steal guns from the police station.
State TV says an 11-year-old boy and a 20-year-old man were killed in the town of Khomeinishahr, while a member of Iran's paramilitary Revolutionary Guard was killed in the town of Najafabad. It says all were shot by hunting rifles.
The towns are all in Iran's central Isfahan province, some 350 kilometers (215 miles) south of Tehran, reports AP.