GENEVA (Reuters) - US Secretary of State Hillary Clinton in a speech to the Conference on Disarmament on Monday said a single country, which she did not identify by name but described as 'a friend and partner of the United States, was blocking the consensus required to launch fissile negotiations in Geneva and build on that momentum. Diplomats and UN officials say that Pakistan is the one holding out on a consensus at the Conference of Disarmament. Negotiations on fissile material outside of the Geneva body could take place in bilateral or small-group sessions. Pakistan has argued repeatedly that existing fissile stocks should also be included in negotiations to counter India's perceived strategic advantage. There is no justification for a single nation to abuse the consensus principle and forever thwart the legitimate desire of the 64 other states to get negotiations underway on an agreement that would strengthen our common security, Clinton declared. She warned nuclear bomb-making fissile material could fall into the hands of terrorists and called for immediate global negotiations to halt its production. She urged the United Nations forum to end its stalemate on fissile talks and indicated that Washington could pursue the issue elsewhere unless there is a breakthrough soon. If we are serious about reducing the possibility that fissile material could fall into terrorists hands, we must reduce the amount of such material that is available, Clinton told the 65-member body in Geneva. As I speak, centrifuges around the world are spinning out more enriched uranium, a still significant amount of it to weapons grade. Plutonium is being churned out in reactors around the world and separated from spent fuel in reprocessing plants, she said, estimating there are 20,000 nuclear weapons worldwide. Clinching a so-called fissile material cut-off treaty would be an important step on the road to a world without nuclear weapons, something US President Barack Obama called for in Prague nearly two years ago, Clinton said. She did not make any reference to Irans nuclear programme, which the United States and other countries fear is aimed at developing nuclear weapons, but which Tehran maintains is for peaceful purposes. Iranian foreign minister Ali Akbar Salehi is due to address the Conference on Disarmament on Tuesday.