The U.S President Barack Obama says the United States and Russia have agreed that additional sanctions could be imposed against Iran if it does not demonstrate that they would not develop nuclear weapons. He was speaking after talks with the Russian President Dmitry Medvedev in New York. The Russian President Dmitry Medvedev has signalled that Moscow might be prepared to soften its opposition to sanctions against Iran over its nuclear plans. Mr Medvedev, speaking after talks with US President Barack Obama, said that in some cases sanctions were inevitable. Mr Medvedev said sanctions were rarely productive but he opened the door to the possibility if Iran pressed ahead with its suspected nuclear weapons programme. Earlier, a Russian official said Moscow could support fresh sanctions if there was enough evidence from UN inspectors. Mr Obama hopes to establish an agreed position ahead of talks next week with Tehran on its nuclear programme.