Iranian security forces may have killed more than 1,000 people during the recent nationwide protests that started over a gasoline price rise, Brian Hook, US Special Representative for Iran, told journalists on Thursday.

He added that “many thousands of Iranians” had also been wounded and at least 7,000 detained in Iran’s prisons.

"As the truth is trickling out of Iran, it appears the regime could have murdered over 1,000 Iranian citizens since the protests began," Mr Hook said, citing reports coming out of Iran on social media.

He said that U.S. officials had seen a video of one incident in which more than 100 people were shot and killed in the southern Iranian city of Mahshahr. The video is said to show protesters being shot at by security forces while running for safety in the marshlands.

The recent unrest in Iran began on Nov. 15 after the government abruptly raised fuel prices by as much as 300%. The protests spread to more than 100 cities and towns and turned political as young and working-class protesters demanded for clerical leaders to step down.

Iranian authorities have yet to publish any definitive official death toll for the unrest that saw protesters attack police stations and torch petrol pumps.

According to the latest Amnesty International report, 208 people are believed to have been killed during the crackdown against the demonstrators.

Tehran’s clerical rulers have blamed “thugs” linked to its opponents in exile and the country’s main foreign foes - the United States, Israel and Saudi Arabia - for the unrest.