UNITED NATIONS - Russian Foreign Minister Sergei Lavrov stayed away from a meeting of six world powers on the sidelines of the UN General Assembly last week because he had to attend another "urgent matter," Russia's UN mission said on Wednesday.Last week, a foreign ministerial-level meeting was convened in New York with the five permanent UN Security Council members - The United States, France, Britain, Russia and China - and Germany. The meeting was inconclusive, diplomats said.European Union foreign policy chief Catherine Ashton also attended the meeting. She said afterword participants had "discussed at length the need for Iran to take action urgently as we considered the Iranian nuclear issue."But in what UN diplomats said could be a sign of the growing divide between Russia and Western powers on Iran and Syria, Lavrov was not at the meeting. Russian UN Ambassador Vitaly Churkin attended instead.