WASHINGTON, March 11: The United States believes that Pakistan is not providing any assistance to Iran’s nuclear programme, a State Department spokesman said on Monday.

“We do believe that Pakistan takes this (nuclear) responsibility seriously,” spokesman Richard Boucher told a briefing in Washington.

He said the United States had all along been telling other governments that “it was not a good idea to cooperate with Iran in nuclear areas.”

Pakistani officials, he said, had said “they do not want to become a source of sensitive technology for Iran and we believe them.”

He said the United States was working with Pakistan to “do all Pakistan can to strengthen controls to ensure that technology cannot fall into the wrong hands.”

Reports in the US media suggested this week that the Natanz nuclear facility in central Iran was close to producing enriched uranium that could be used in nuclear arms.

The reports warned that Iran hoped to complete this complex in 2005, which would allow it to produce enough uranium for several nuclear bombs each year.

Commenting on these reports, Secretary of State Colin Powell said on Sunday that Iran had a more developed nuclear weapons programme than previously thought.

Iran has rejected all such allegations. “Such remarks are a continuation of US interference in Iran’s domestic affairs,” Iran’s Foreign Ministry spokesman Hamid Reza Asefi told the Islamic Republic News Agency.

“Iran’s nuclear programme is in accordance with realities and in our opinion the United States tries to thwart the constructive cooperation between the Islamic republic of Iran and the International Atomic Energy Agency,” Mr Asefi said.