Both Obama and Russian President Dimitry Medvedev, who spoke later, noted that the world's two nuclear superpowers were working on reducing their stockpiles in advance of a global nuclear summit scheduled for next year.

'It's obvious that an effective solution ... depends on the constructive engagement of all parties,' Medvedev said, adding that he expected the Russia-US leadership on the issue to be backed by 'all nuclear powers'.

On Wednesday, Medvedev signalled he could support sanctions against Iran over its efforts to develop a nuclear weapon.

'Russia's position is clear: sanctions rarely lead to productive results, but in some cases sanctions are inevitable,' Medvedev said in a joint appearance with Obama after they met in New York.

The statement bolsters US-led efforts for increased international pressure on Iran to adhere to non-proliferation agreements in pursuing the development of nuclear energy.

Iran claims its nuclear programme is intended for peaceful purposes, but the international community accuses it of continuing to try to develop nuclear weapons capability.