US State Secretary Hillary Clinton on Sunday warned Iran that Washington is working with its partners on moves to convince the Islamic republic to change course in its nuclear drive.

"Iran leaves the international community little choice but to impose greater costs for its provocative steps," Clinton said in a speech at the US-Islamic World forum in Doha.

"Together, we are encouraging Iran to reconsider its dangerous policy decisions," the US diplomatic chief said.

"We are now working actively with our regional and international partners, in the context of our dual track approach, to prepare and implement new measures to convince Iran to change its course.

"Iran has consistently failed to live up to its responsibility. It has refused to demonstrate to the international community that its nuclear programme is entirely peaceful," Clinton said.

The US diplomatic chief said US endorsement of an offer to provide Iran with fuel for the Tehran Research Reactor "demonstrated good-faith commitment to working with Iran" towards a peaceful civil nuclear programme.

But she scolded Tehran for refusing the terms of the UN atomic watchdog, the International Atomic Energy Agency.

"This has only deepened the international community's doubts about Iran's nuclear intentions, along with the Iranian government's own isolation," she said.

Iran, which rejects accusations of seeking to build a nuclear bomb, said last Tuesday that it has started the process of producing 20 percent enriched uranium, defying Western threats of fresh sanctions.