At least 304 people have been killed in Iran during anti-government unrest that broke out last month, Amnesty International said on Tuesday.Thousands have been arrested including children as young as 15 in a crackdown that followed the protests, London-based Amnesty said in a statement."At least 304 people were killed and thousands were injured between 15 and 18 November as Iranian authorities crushed protests using lethal force," it said.Amnesty said earlier this month that at least 208 were killed in the protests. Iranian authorities have dismissed Amnesty's previous figures and have yet to give a death toll from the deadliest protests In Iran in decades.Hundreds of young and working-class Iranians took to the streets on Nov. 15 to protest against fuel price rises. The protests immediately turned political, with demonstrators burning pictures of senior officials and calling on clerical rulers to step down.Iranian authorities earlier this month acknowledged that some "rioters" were shot and killed by security forces. Supreme Leader Ayatollah Ali Khamenei denounced the unrest as a "very dangerous conspiracy" by Iran's enemies.Amnesty said Iranian authorities had carried out a "wide-scale clamp down designed to instill fear and prevent anyone from speaking out about what happened.""Iran's authorities are...arresting thousands of protesters as well as journalists, human rights defenders and students to stop them from speaking out about Iran's ruthless repression," it said.On Dec 6, the United Nations human rights office said at least 208 people have been killed but the real toll could be twice that. At least 7,000 people had been arrested, it said.