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.
Last week, a 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 afterward that 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.
A spokesman for Russia's UN mission confirmed Lavrov's absence, saying Wednesday: "The minister had to attend to some other urgent matter, as far as I know."
Chinese Foreign Minister Yang Jiechi attended, envoys said.
The meeting of the "P5-plus-one" group came the same day, last Thursday, that Israeli Prime Minister Benjamin Netanyahu drew his "red line" for Iran's nuclear program, saying Tehran may be on the brink of an atomic bomb in less than a year.
He suggested that Israel might have to decide whether to attack Iran's nuclear facilities by spring 2013.
Iran is under UN, U.S. and EU sanctions for refusing to halt nuclear enrichment, which Western powers and their allies fear is part of a plan to amass the capability to produce nuclear weapons. Tehran denies the charge, saying its atomic work is for medicine and electricity generation.
Diplomats said calls for additional EU sanctions against Iran by Britain, France and Germany ahead of the UN General Assembly session could have been a reason for Lavrov's absence. Moscow has repeatedly criticized unilateral U.S. and EU sanctions against Tehran.
One senior Western diplomat said the Security Council would never adopt another round of sanctions against Iran because of Russian and Chinese resistance.
Russia and China have reluctantly supported four rounds of UN sanctions against Iran over its nuclear program, but they have worked hard to water down the measures in negotiations on the Security Council resolutions prior to their adoption.