The Bush administration has refused to speculate on what the disgraced Pakistani scientist A Q Khan's input may have been in the North Korean nuclear blast.

"I don't know who's talked to him (A Q Khan) lately. But he's out of business, and that's a good thing for nonproliferation efforts around the world," State Department spokesman Sean McCormack.

He was replying to a question on whether Khan, 'the mentor' of North Korea, had been interviewed by both the United Nations and the International Atomic Energy Agency because he would know 'where all the pieces' lay.

In the meantime Secretary of State Condoleezza Rice [Images] said the US was still trying to figure out what really happened in North Korea.

"We're still trying to evaluate what really happened here. And I think it will take a little while to evaluate it. But we have to take the claim seriously because it's a political claim if nothing else that tries to get the bargaining position of being a nuclear power," Rice said in an interview to CNN.

"I think it's very obvious that they were pursuing another path to a nuclear weapon, a so-called highly enriched uranium path. But the important thing here is that we now have an opportunity with the international community speaking with one voice to bring world pressure on the North Koreans to make a different choice than they have made over this decade," Rice said.

She also said that leaders of North Korea, Iran and Iraq were looking to the guarantee of nuclear weapons so that the United States and allies did not invade them.

"I think we shouldn't even allow them such an excuse," Rice said also making the point that she has never seen the 'universal' condemnation of the kind that Pyongyang is now facing.

Asked what Washington means when it said that Kim Jong Il is going to 'rue the day', Rice replied, "Because this already isolated regime, I think is going to find itself even more isolated and ultimately the regime itself has things that it wants from the international system. Foggy Bottom is still saying that it cannot confirm or deny if North Korea's test was nuclear or not."

"Obviously our intelligence experts are looking at all their oscilloscopes and whatever else they look at to determine these various things. There's a lot of different pieces of the puzzle that go into this. At this point, I can't tell you. When and we if we do -- are able to determine exactly the nature of the cause of the seismic event, then we'll certainly try to keep you informed," McCormack said at his regular briefing.