Pakistan acknowledged yesterday for the first time that a disgraced Pakistani scientist at the centre of a nuclear black market gave Iran centrifuges which can be used to make atomic weapons.
Centrifuges purify uranium for use as fuel in atomic power plants or bombs. Washington believes Iran's centrifuge programme, which it concealed from UN inspectors for nearly two decades, is at the heart of clandestine atom bomb plans.
Tehran says its enrichment programme will produce only low-grade enriched fuel for power plants, not highly enriched uranium for weapons.
"(Abdul Qadeer Khan) has given centrifuges to Iran, but the government was in no way involved in this," Pakistani Information Minister Sheikh Rashid Ahmed said.
Pakistan has admitted in the past that Khan, dubbed the father of Pakistan's atomic bomb, smuggled nuclear secrets to North Korea, Iran and Libya. But this is the first time Islamabad admitted that Khan supplied Iran with centrifuges.
The UN International Atomic Energy Agency (IAEA) was not surprised by Pakistan's public confirmation of Khan's role in Iran's programme. "We're well aware that Iran received designs and centrifuge components from the Khan network," IAEA spokesman Melissa Fleming said.
The agency has found no clear proof of an Iranian nuclear arms programme, but is not convinced Iran declared everything.
One Western diplomat in Vienna, where the IAEA is based, said Khan clearly knows the answer to the question of whether or not Iran wanted the bomb when it first made contact with Khan's clandestine nuclear network in 1987.
"Khan is the man who would know if the Iranians wanted nuclear weapons," the diplomat said on condition of anonymity, adding that it was a pity Islamabad refuses to allow the IAEA to question Khan directly. Several Vienna diplomats said there is no way Islamabad was entirely unaware of Khan's atomic peddling.
In November 2004, the Iranian exile group that first outed Tehran's nuclear programme, the National Council of Resistance of Iran, said that between 1994 and 1996 Khan gave Iran the same Chinese design for a nuclear warhead that he had given Libya.
Mohamed ElBaradei has called Khan's massive black market, with tentacles in Europe, Africa, the Middle East and Asia, a virtual "supermarket" for states seeking the bomb.
A.Q. Khan, revered in Pakistan as the man who secured for Pakistan the nuclear arms capability to balance that of nuclear armed neighbour and rival India, admitted last year to selling nuclear technology and made a televised apology to the nation.
The scandal was a severe embarrassment for Pakistan, the only Muslim state known to have nuclear weapons, and raised fears that weapons of mass destruction could fall into the hands of militants or rogue states.
Khan remains under close guard at his home in Islamabad, although authorities deny he is under house arrest, though they refuse to allow him to be questioned by the IAEA.
"We will not hand over Dr Qadeer to any other country," Mr Ahmed reiterated yesterday.
However, IAEA's Ms Fleming said that it was getting "good cooperation from Pakistan" in its probe of the extent of nuclear technology Iran received from Khan and his associates.
As French, British and German officials began a new round of talks with Iranian negotiators in Geneva on Tuesday, Tehran threatened to break off negotiations if they continued to insist that Iran abandon all sensitive atomic activities.