WASHINGTON, Dec 5: President George W. Bush has urged President Gen Pervez Musharraf to obtain more information from Dr A. Q. Khan but did not ask for direct access to the scientist, US officials said.

Briefing reporters after an unusually warm and cordial meeting between Gen Musharraf and President Bush at the White House on Saturday, the officials played down media reports of tension with Pakistan over continuing US efforts to learn more about the so-called Khan network of nuclear proliferators.

Pakistan has refused to allow US or International Atomic Energy Agency investigators to interrogate Dr Khan but has offered to share whatever information it retrieves from the scientist.

The issue was raised again at the closed meeting between the two presidents on Saturday, which was also attended by Vice-President Dick Cheney, Defence Secretary Donald H. Rumsfeld, outgoing Secretary of State Colin L. Powell and his designated successor, National Security Adviser Condoleezza Rice.

A senior administration official told journalists that President Bush had raised the issue only obliquely asking Gen Musharraf to assure that there would be continued cooperation. The official said President Musharraf "didn't seem aware that there was any problem" and promised to look into it.

The official said the United States had already obtained "a treasure trove" of information from Pakistan about the Khan network. "But we need to go back and make sure we've gotten every nook and cranny," he added.

President Musharraf, he said, had promised "that he was going to take this on when he gets back to Islamabad and make sure that the information that is available is fully shared".

In his interview to the Washington Post published on Sunday, Gen Musharraf ruled out granting any outsiders access to Dr Khan because it would ignite anger among a public that has long revered him as the father of Pakistan's nuclear bomb. "It's a very sensitive issue inside Pakistan," he said. "The man has been a hero for the people." In addition, Gen Musharraf said he considered any such request a personal affront. "It shows a lack of trust."