VIENNA (Reuters) - The United States, which has accused Iran of having a nuclear weapons program, said on Wednesday it was confident the U.N. atomic watchdog would warn Tehran it could face sanctions within months.

Iran said Washington was bullying members of the United Nations into criticizing its nuclear program and this could complicate the Islamic Republic's future cooperation with the International Atomic Energy Agency (IAEA).

Secretary of State Colin Powell said a resolution being discussed would stop short of declaring Iran in breach of IAEA rules and reporting it to the U.N. Security Council for possible sanctions but would signal this could be close.

"What we have insisted on is that there has to be language in this resolution that causes the IAEA to review the situation at the next meeting," Powell told a congressional hearing.

"Then in June make a judgment as to whether further action should be required and whether there should be other referrals to the Security Council, and that language I am confident...will be reflected in the resolution," he said.

Iran says its nuclear program is purely peaceful, but the draft resolution suggests it is military-linked.