Foreign Ministry spokesman Mohammad-Ali Hosseini advised Washington "to be more patient" if it was to prove its honesty in supporting the path of negotiations and diplomacy in solving Iran's nuclear case, IRNA said.

Iran believes that the negotiation is "the only way out" of its current nuclear standoff with the West, the new Iranian Foreign Ministry spokesman was quoted as saying.

Hosseini was commenting on recent remarks by U.S. State Department spokesman Sean McCormack who accused Iran of trying to string out the diplomatic contacts to avoid punitive action of the United Nations.

"We've seen this game before from the Iranians. They want to stretch things out...It's time to act through the (UN) Security Council, and it's time to impose sanctions on Iran," McCormack said Wednesday.

Hosseini dismissed the U.S. official's remarks, saying that Washington was "seeking to advance its own goals in a threatening and bullying manners."

The United States was "to poison the atmosphere of nuclear talks and derail it through its anti-Iran propaganda," the Iranian Foreign Ministry spokesman said.

Gregory Shulte, the U.S. representative to the Vienna-based International Atomic Energy Agency (IAEA), also said Wednesday that sanctions should be imposed on Iran if it still refuses to comply with the UN Security Council resolution.

Speaking at the IAEA meeting of the Board of Governors, Shulte said, "Iran's refusal to suspend and its refusal to cooperate is a choice of confrontation over negotiation."

"Time has come for the Security Council to back international diplomacy with international sanctions," he said. The UN Security Council adopted a resolution in late July, urging Tehran to suspend by Aug. 31 all enrichment-related and reprocessing activities, including research and development, or face prospect of sanctions.

IAEA chief Mohammed ElBaradei has presented a report to the Security Council saying that "Iran has continued enriching uranium despite a UN nuclear deadline for it to suspend or face possible sanctions."

At an informal meeting in Brussels earlier this month, European Union foreign ministers decided to maintain serious talks with Tehran in efforts to solve Iran's nuclear issue through diplomacy.