Clinton was speaking in London after talks with Russian Foreign Minister Sergei Lavrov, part of a series of meetings focused on Iran held on the sidelines of international conferences on Afghanistan and Yemen.

Russia -- which along with China has been less eager to push for new U.N. sanctions on Tehran -- was now "very willing" both to work with the United States and to consider "appropriate pressure" as a next step, she said.

"In the course of many consultations including today we believe that there is growing understanding in the international community that Iran should face consequences for its defiance of international obligations," Clinton told reporters.

Lavrov, speaking to Russian reporters after the meeting, stopped short of openly supporting new sanctions. But he warned that patience with Tehran was running out, according to remarks quoted by state-run RIA Novosti.

"It is clear that one can't wait forever, and our partners are already talking about the need to discuss further measures in the U.N. Security Council," he said.

Clinton, who is officially in London to focus on Afghanistan and Yemen, is nevertheless engaged in extensive diplomacy on Iran, trying to win support from both Russia and China for new sanctions if Tehran does not act to ease concerns over its nuclear program.

Tehran says its only goal is generating nuclear energy, but Washington accuses it of trying to develop nuclear weapons.

Russia and China approved three previous rounds of sanctions against Iran but used their clout to water them down. The Kremlin has indicated it could support new sanctions but also cautioned against rushing to punish Iran, saying that this could be counterproductive.

WHAT ABOUT CHINA?

Clinton and another senior U.S. official involved in the discussions characterized Russia's position as supportive of the U.S. effort, with the U.S. official saying only "tactics" over eventual sanctions needed to be worked out.

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