A key rally against Iran's presidential elections will go ahead on Saturday - in defiance of Supreme Leader Ayatollah Khamenei - opposition sources say. The wife of defeated candidate Mir Hossein Mousavi, and an aide to another rival candidate Mehdi Karroubi, said the rally would go ahead. Ayatollah Khamenei has warned that protest leaders would be responsible if new marches led to violence. The powerful Guardian Council is also due to hear the candidates' complaints. Fresh protests had been planned for Saturday, but in the wake of the ayatollah's warning it was not clear if they would go ahead. On her page of the social networking website Facebook, Mr Mousavi's wife Zahra Rahnavard said the rally would go ahead. An aide to Mr Karroubi also told the BBC that a rally would take place and that it would be attended by Mr Mousavi and Mohammad Khatami - the former president, key reformist and ally of Mr Mousavi. Iranian officials have warned protest leaders not to launch fresh demonstrations. Abbas Mohtaj - head of Iran's State Security Council and also deputy interior minister - issued a direct warning to Mr Mousavi. "Should you provoke and call for these illegal rallies you will be responsible for the consequences," he said in a statement. 'Bloodshed' Official results of the 12 June presidential poll gave President Mahmoud Ahmadinejad a resounding 63% of votes, compared to 34% for his nearest rival, Mir Hossein Mousavi. The result has triggered almost daily street protests - a challenge to ruling authorities unprecedented since the Islamic revolution of 1979. The human-rights group Amnesty International says it believes about 10 people have been killed. On Friday, US President Barack Obama warned Iran that the "world is watching" events there. He expressed concern at "some of the tenor and tone of the statements that have been made". A new rally on Saturday would directly challenge an order from Ayatollah Khamenei, Iran's spiritual leader and highest authority. "Straight challenge is not acceptable after the election," Ayatollah Khamenei told thousands of Iranians who massed to hear him on Friday. "This is challenging democracy and election itself. I want every side to put an end to this method. If they don't then the responsibility of its consequences, the riots should be shouldered by those who do not put an end to it." The ayatollah insisted the Islamic Republic would not "cheat voters" - and blamed foreign powers, in particular the UK, for fomenting the unrest. He said "bloodshed" would result if the protests went ahead. The rally was attended by President Ahmadinejad. But former President Rafsanjani, who is backing the opposition, did not attend. Although the Supreme Leader controls many levers of power, Mr Rafsanjani heads the Assembly of Experts, which has the power to elect the leader, supervise him, and theoretically even to dismiss him, our correspondent says. Behind the scenes, he says, there appears to be both a political battle between two veterans of the Islamic Revolution, but also a titanic dispute about the whole future of Iran, whose outcome no-one can predict. In Saturday's meeting of the Guardian Council, Mr Mousavi was expected, along with fellow challengers Mehdi Karroubi and Mohsen Rezai, to discuss more than 600 objections they had filed complaining about the poll. But the Guardian Council, which is the body which certifies the election, has so far only offered a partial recount of disputed ballots from the election. Source: BBC