Assistant Secretary of State for arms control Stephen Rademaker said the United States is "very sceptical of Iran's good faith in these negotiations."

He told journalists on the sidelines of a meeting in Vienna of the Organization for Security and Cooperation in Europe (OSCE) that the United States has "told our European allies that we will not stand in the way of their effort to come to some diplomatic understanding with Iran."

But he said: "We do not expect Iran to comply over the long-term with any commitment not to develop nuclear weapons."

Rademaker said Iran was "more like North Korea," which has pulled out of the nuclear Non-Proliferation Treaty (NPT) and says it has nuclear weapons than Libya, which has abandoned a secret nuclear program and submitted to full verification from the IAEA.

"I think the question we should all ask looking at Iran today is Iran more like North Korea or like Libya. I think it is quite obvious that Iran is a lot more like North Korea than it is like Libya," Rademaker said.

"We have made clear that our view is that Iran is seriously embarked on an effort to develop nuclear weapons in violation of Iran's obligations as a non-nuclear weapons state under the nuclear Non-Proliferation Treaty," Rademaker said.

An Iranian negotiator, Hossein Moussavian, said Sunday that Iran and the European Union have reached a "preliminary agreement" on easing concerns over the Islamic republic's nuclear programme following two days of crucial negotiations in Paris.

The accord is centered on demands that Iran maintain and widen a suspension of its sensitive uranium enrichment activities or else risk being referred by the UN nuclear watchdog, the International Atomic Energy Agency (IAEA), to the UN Security Council for possible sanctions.

According to European diplomats, the tentative deal still contains several sticking points -- including the length and extent of any halt on fuel cycle work.

The United States wants the IAEA to send the Iranian dossier to the Security Council.

Iran says its nuclear program is strictly peaceful and wants the IAEA to "noramlize" the Iranian dossier.

But Rademaker said Iran's pursuit of a long-range missile program, in conjunction with its sophisticated nuclear program, showed non-peaceful intentions.

Iran is capable of mass-producing the Shahab-3, a ballistic missile capable of hitting Israel, Defence Minister Ali Shamkhani said in Tehran Tuesday.

Rademaker said: "This coincidence of a nuclear weaopns program and a long-range missile program is not a coincidence. It's something one would predict for a country that has made a strategic decision to become a nuclear power."

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.