Dubai: Riot police and security forces have clashed with demonstrators in Tehran and dozens of cities across Iran, Iranian news agencies and social media say, as protests against a rise in petrol prices turned political.

The reports said demonstrators chanted anti-government slogans around the country on Saturday, a day after the government increased the price of regular petrol to 15,000 rials (52¢) a litre from 10,000 rials (35¢) and rationed it.

Large protests across highways and in the streets have left six dead, according to reports, after the government increased the fuel price. Credit:AP

State television said police clashed with what it called rioters in some cities and fired tear gas to disperse them.

At least six people were dead after security forces clashed with protesters, according to Persian language news outlets.