MOSCOW (Reuters) - Russia warned US lawmakers on Monday that any changes to the strategic nuclear arms limitation treaty signed by Presidents Barack Obama and Dmitry Medvedev in April could kill the pact. Foreign Minister Sergei Lavrovs warning, in an interview with the Interfax news agency, came with the White House pressing for a ratification vote on the New START treaty this week before the Senate breaks for Christmas. Some US Republicans want to make changes in the treaty, which they say could limit US national security options, and to the accompanying ratification resolution before voting. Democrats, whose Senate majority was reduced in congressional elections last month, have moved to bring the treaty to a vote this week before the new chamber takes office in January. It needs 67 votes for approval in the 100-member Senate. I can only underscore that the Strategic Nuclear Arms Treaty, worked out on the strict basis of parity, in our view fully answers to the national interests of Russia and the United States, Interfax quoted Lavrov as saying in an interview. It cannot be opened up and become the subject of new negotiations, Lavrov said. Medvedev has told Russias Kremlin-controlled parliament not to ratify the pact, a key element of improving relations between the Cold War foes, until US Senate approval comes through or is certain. Parliament could potentially sign off on it this year if the Senate approves it in time, said Konstantin Kosachyov, Kremlin-allied chairman of the international affairs committee in the State Duma, the lower chamber. But he said Russian lawmakers would closely examine the US ratification resolution and any declarations or notes accompanying it to ensure no significant changes were made. Its just impossible to say in what form we will ratify the pact without seeing the final Senate texts, Kosachyov said.