PRAGUE - Prague has agreed to host the signing of a new US-Russian treaty to reduce long-range nuclear weapons, the Czech Foreign Ministry said Wednesday. The announcement is the clearest sign yet that Washington and Moscow are close to completing the deal on an accord to replace the 1991 Strategic Arms Reduction Treaty, or START, which expired in December. Ministry spokesman Filip Kanda said that Prague agreed to host the signing of the accord by US President Barack Obama and Russian President Dmitry Medvedev when the negotiators reach a deal. He said negotiations have not been completed yet. "As an ally, we have consulted with the US side on an option for us to complete the signing when a deal is done," Kanda said. "We've agreed," he said. It was not clear if the plan for the signing ceremony had also been discussed with the Russian government. Kanda declined to comment on that. In Washington, a senior Obama administration official said the White House has talked to both the Czech and Russian governments about a signing in Prague. The official, speaking on condition of anonymity to discuss still-ongoing and sensitive negotiations, said a deal is still being finalised. For Obama, signing the treaty in Prague would be a symbolic return to the city where he outlined his nuclear agenda in April and declared his commitment to "a world without nuclear weapons" in a sweeping speech before a crowd of many thousands.