MOSCOW- Russian Foreign Minister Sergei Lavrov said on Tuesday it was a mistake for UN chief Ban Ki-moon to withdraw an invitation to Iran to attend peace talks on Syria, but did not see it as a catastrophe.Lavrov said the Syrian opposition had in effect held the peace conference known as Geneva-2 to ransom by saying it would not attend if Iran was invited, and suggested the confusion had done nothing to boost the standing of the United Nations."It is, of course, a mistake ... But it isn't a catastrophe," Lavrov told a news conference in Moscow.He said Moscow stood by its position that all interested parties should be involved in the conference on ending almost three years of civil war."The absence of Iran will not contribute to efforts to ensure the unity of the Muslim world, including in fighting terrorism, which is a threat to all of us and all Muslims as well," Lavrov said.He added: "I just feel sorry that the events have not increased the authority of the United Nations."Ending nearly 24 hours of confusion that dismayed diplomats who have spent months cajoling opponents to President Bashar al-Assad to negotiate, Ban's spokesman said on Monday Iran was no longer welcome at the initial day of talks at Montreux, Switzerland, on Wednesday.Ban, his spokesman said, made the invitation to Iran after Iranian officials assured him they supported the conclusion of a UN conference in 2012, known as Geneva-1, which called for a transitional administration to take over power in Syria, something neither Assad nor Tehran have been willing to embrace.On Monday, Iranian officials made clear that they were not endorsing that conclusion as a basis for the talks.