TEHRAN // Iranian authorities banned a planned protest rally by supporters of Mir Hussein Mousavi in Tehran today, but the defeated presidential candidate said he would attend anyway to calm the crowd. Protests marking the sharpest display of discontent in the Islamic Republic in years have rocked the capital since the interior ministry announced on Saturday that the president Mahmoud Ahmadinejad had won Friday's election by a big margin. The ministry and Mr Ahmadinejad have rejected charges of fraud levelled by losing candidates. Mr Mousavi, who has appealed to the watchdog Guardian Council to annul the result, had asked supporters to rally today. But the interior ministry declared any such gathering would be illegal and seditious, warning that it would hold the former prime minister responsible if the event went ahead. "The consequences of such behaviour will be directed at Mousavi," its director general of political affairs, Mahmoud Abbaszadeh Meshkini, said, the state IRNA news agency reported. Mr Mousavi's website said the rally had been postponed, but added the moderate opposition leader would go to the venue to ensure any supporters who showed up remained calm. The Supreme Leader Ayatollah Ali Khamenei, who has upheld the election result, met Mr Mousavi yesterday and told him to pursue his complaints "calmly and legally", state television said. The election outcome has disconcerted Western powers trying to induce the world's fifth-biggest oil exporter to curb nuclear work they suspect is for bomb-making, a charge Iran denies. France, which has sharply criticised the election, said it backed Iranian opposition calls for an inquiry into the vote. "I asked today that the investigations demanded by the opposition be carried out," the French foreign minister Bernard Kouchner told reporters after discussing the election with EU colleagues. The European Union urged Iran not to use violence against protesters and to look into complaints of irregularities. Britain voiced concern about the impact of events in Iran on any possible international engagement with its government. "The implications are not yet clear," said the British foreign secretary David Miliband. "What we know is that there has been no Iranian response to the outreach that has been made by the international community, including the United States." US leaders have reacted cautiously, in the hope of keeping alive president Barack Obama's strategy of engagement with Iran. The Guardian Council, whose chairman, Ayatollah Ahmad Jannati, endorsed Mr Ahmadinejad before the vote, said it would rule within 10 days on two official complaints it had received from Mr Mousavi and another losing candidate, Mohsen Rezaie. "Mousavi and Rezaie appealed yesterday. After the official announcement (of the appeal) the Guardian Council has seven to 10 days to see if it was a healthy election or not," ISNA news agency quoted council spokesman Abbasali Kadkhodai as saying. The council vets election candidates and must formally approve results for the outcome to stand. Mr Ahmadinejad delayed a visit to Russia today for a regional summit, an Iranian embassy source in Moscow said, giving no reason. The source said the president would arrive tomorrow. About 400 pro-reform students, many wearing green face masks to conceal their identity, gathered at a mosque in Tehran University and demanded Mr Ahmadinejad's resignation. "We will stage a sit-in inside the university from Tuesday until the vote results are cancelled," said one student. Some said religious militia had attacked their dormitory. "They hit our friends and took away at least 100 students. We have no news about their whereabouts," said another student. University officials denied the reported incidents. *Reuters