The United States on Friday ruled out any contact with Iranian delegates to an international aid conference that comes just before next week's showdown vote on whether to send Iran to the UN Security Council over its disputed nuclear program. Secretary of State Condoleezza Rice leads a US delegation to the two-day conference in London on international aid for rebuilding Afghanistan. On Thursday, the day after the session closes, the Vienna-based UN nuclear watchdog agency is set to vote on Iran's case. "I do not anticipate, and I'm 100 percent sure about this, any contact between whichever official is sent by the Iranian government and our delegation, including Secretary Rice," said Undersecretary of State Nicholas Burns. "In an environment where the new Iranian president has called for the destruction of Israel, has denied that the Holocaust happened as a historical fact, has put Iran on a more radical course on its nuclear policy, has continued Iranian support for terrorism, there's not a lot to talk about," Burns said.