Ten people have been killed overnight in anti-government protests sweeping Iran, according to state TV.

"In the events of last night, unfortunately a total of about 10 people were killed in several cities," it said. At least 12 people have now died since protests began on Thursday, Axar.az reports.

The unrest continued despite a call for calm from President Hassan Rouhani.

In his first intervention, President Rouhani warned on Sunday that violence would not be tolerated.

Mr Rouhani acknowledged grievances over Iran's economic situation, a lack of transparency and corruption, but defended his record.

The Iranian president said that citizens were "completely free to express their criticism of the government or stage protests... in a way that would lead to the improvement of the country's conditions" but warned against violent acts.

Nevertheless, protests continued overnight. Police used tear gas and water cannon to quell a rally in Tehran's Engheleb Square and demonstrations were reported in Kermanshah and Khorramabad in the west, Shahinshahr in the north west and the northern city of Zanjan.

The demonstrations, which erupted on Thursday in Iran's second city of Mashhad, are the biggest show of dissent seen since the huge rallies of the Green Movement were brutally suppressed in 2009.