Iranian opposition leader Mir Hossein Mousavi has urged his supporters to continue protesting over the re-election of President Mahmoud Ahmadinejad. Mr Mousavi also made a veiled appeal to the security forces to show restraint in handling demonstrations. The conservative leadership has vowed to use force wherever necessary to quell the opposition's demonstrations. On Sunday, gunfire was heard in the north of Tehran, a bastion of support for the reformist former prime minister, as helicopters hovered overhead. "Protesting against lies and fraud (in the election) is your right," Mr Mousavi, who came a distant second to Mr Ahmadinejad in the poll, said in a statement on his website on Sunday. "In your protests, continue to show restraint. I am expecting armed forces to avoid irreversible damage," he added. Iranian state TV said ten people were killed and more than 100 others injured in protests in Tehran on Saturday held in defiance of a warning from Supreme Leader Ayatollah Ali Khamenei. A separate report put the number of deaths at 13. Mr Mousavi said the mass arrest of his supporters "will create a rift between society and the country's armed forces". A product of the Islamic establishment himself, Mr Mousavi said on Saturday he was not questioning the fundaments of the Islamic Republic but sought to renew it and purge it of what he called deceit and lies. The June 12 election which returned the anti-Western Mr Ahmadinejad to power has sparked the most violent unrest since the 1979 Islamic Revolution which ousted the Shah. The authorities have branded the protesters as "terrorists" and rioters. Tehran's police commander Azizullah Rajabzadeh warned police would "confront all gatherings and unrest with all its strength". US President Barack Obama, in the forefront of diplomatic efforts to halt an Iranian nuclear programme the West fears could yield atomic weapons, has urged Iran to stop violence against protestors. German Chancellor Angela Merkel said the authorities should conduct a recount. Mr Ahmadinejad has rejected such calls as western interference. An analysis of official statistics from Iran's Interior Ministry by Britain's Chatham House think-tank suggested that in the conservative Mazandaran and Yazd provinces, turnout was more than 100 per cent. It said that in a third of all provinces, official results would have required Mr Ahmadinejad to take all former conservative, centrist and all new voters, and up to 44 per cent of reformist voters, "despite a decade of conflict between these two groups". The authorities reject charges of election fraud. But the highest legislative body has said it is ready to recount a random 10 per cent of votes cast.