A Republican US senator said Tuesday he will try to block a US-Russia civilian nuclear power deal if President George W. Bush sends it to Congress, because he fears it could undermine efforts to prevent nuclear proliferation in Iran. Under the deal signed Tuesday, the United States would get access to Russian state-of-the art nuclear technology. The pact would help Russia establish an international nuclear fuel storage facility by importing and storing spent fuel. The United States controls most of the world's nuclear fuel by far. "I am very disappointed by the administration's insistence on moving forward to sign a nuclear cooperation arrangement with the Russians," Sen. Norm Coleman said in a telephone interview. "Particularly at a time when Russia's actively undermining our foreign policy on various fronts, most importantly with respect to Iran." In a statement, Democratic Sen. Evan Bayh said: "US-Russian nuclear cooperation is important, but stopping Iran from gaining the capacity to make nuclear weapons is an even higher priority. Russia is not doing all it can to curb Teheran's nuclear ambitions, and we need to use all tools at our disposal to get more cooperation from Moscow."