WASHINGTON, March 11: The US State Department has said that it is concerned over the disclosure that the Dr Abdul Qadeer Khan?s network had provided Iran with centrifuges to enrich uranium.

Commenting on the first public statement by a Pakistani federal minister about the nature of transferred nuclear technology to Iran, State Department?s deputy spokesman Adam Ereli told a Thursday afternoon briefing in Washington that this was a cause of great concern for his government.

?Obviously, we view with great concern any indication that Iran is involved in or desires of obtaining material to support a nuclear weapons programme,? Mr Ereli said.

Washington is mounting pressure on Iran to give up its alleged nuclear weapons programme which Tehran insists is for peaceful purposes. Diplomatic observers in Washington pointed out that the new nuclear controversy comes days before a visit to Pakistan by US Secretary of State Condoleezza Rice.

They said that originally Ms Rice had not planned to raise the nuclear issue with the Pakistanis during her visit next week. ?But now it will be difficult for her to ignore the public acknowledgement of a cabinet minister,? said a senior South Asian diplomat.

But other diplomatic sources, also from South Asia, say that there?s nothing in the statement that the Americans did not already know. According to these sources, the United States has maintained regular contact with the Pakistanis on this issue ever since Dr Khan confessed to selling N-tech to these three states.