A top U.S. official on Wednesday stepped up overtures to Iran to prove that it wants a nuclear proliferation deal with the West.
"We should be cautious but cognizant of potentially historic opportunities," Rose Gottemoeller, U.S. assistant secretary of state for arms control told a UN disarmament committee, according to AFP.
"We must continue to push to bring Iran back into line with its international nuclear obligations," Gottemoeller told the forum, which included Iranian diplomats.
"The United States is ready to talk. We are ready to listen. We are ready to work hard and we hope that every country in this room is ready to do the same," Gottemoeller said.
"The road toward the next steps might not be familiar and it will require difficult negotiations and complicated diplomacy," she added.
Western nations say they are waiting for the Iranian government to follow up on statements made by President Hassan Rouhani that his country wants an accord to end western doubts about Iran's nuclear drive.
The United States, Britain and France say they believe Iran seeks a nuclear bomb capability. Iran, which is under several rounds of UN sanctions over its uranium enrichment, denies the charge.
European foreign policy chief Catherine Ashton - negotiating for the United States, Russia, Britain, France, Germany and China - is to meet with Iranian negotiators in Geneva next Tuesday.
Western diplomats say this will be a first chance to test Iran's intentions. Rouhani said he wanted a deal within a year. U.S. President Barack Obama has insisted though that Iran must follow up with concrete actions.
According to the Wall Street Journal, Iran has prepared a set of proposals that it will take to a meeting in Geneva next week as its bargaining chip to see crippling sanctions lifted from the country.
As an opening position in negotiations with the P5+1 group, the newspaper has said Tehran will offer to stop enriching uranium to levels of 20% purity, a level considered close to that needed to make nuclear weapons.