Bush revealed the phone call in a solo White House news conference, and said the move was "part of an ongoing process" to encourage Hu "to stay involved in the process of discussion" with North Korean leader Kim Jong.

China, seen as one of the few states with any influence in Pyongyang, has mounted months of diplomacy designed at finding a format acceptable to both North Korea and the United States for talks on the crisis which erupted last October.

The Stalinist state has demanded one-on-one consultations with Washington, but the Bush administration has refused, arguing the showdown is a regional crisis and should therefore be solved with input from key powers like China, South Korea and Japan.

"I told President Hu that it is very important for us to get Japan and South Korea and Russia involved as well," Bush said.

"We are actually beginning to make serious progress about sharing responsibility on this issue, in such a way that I believe will lead to an attitudinal change by Kim Jong Il," he said.

"I think that one of the things that is important to understanding North Korea is that the past policy of trying to engage bilaterally didn't work," Bush spoke.

"In other words, the North Koreans were ready to engage, but they didn't keep their word on their engagement.

Bush spoke after US envoy John Bolton held talks with South Korean Foreign Minister Yoon Young-Kwan in Seoul on the crisis, and the North reiterated a demand for one-on-one talks.

Bolton, undersecretary of state for arms control and international security, told Yoon North Korea was considering a US proposal for a resumption of three-party talks also involving China which last convened in April.

He said broader multilateral talks would then follow, according to a South Korean official.

The US proposal was submitted to North Korea by China following Chinese Deputy Foreign Minister Dai Bingguo's return last week from a trip to Washington.

But in the diplomatic fog which clouds all dealings with reclusive North Korea, there have also been signs that China's diplomatic drive for talks to end the nuclear crisis was running out of steam.

Beijing dispatched Dai to Pyongyang earlier this month for talks with reclusive Kim Jong-Il and then sent him on to Washington for talks with Secretary of State Colin Powell and top White House officials.

On the eve of Bolton's arrival, Yoon said Chinese consultations with North Korea had slowed and it was unclear when a new round of talks would take place.

North Korea on Wednesday, in public at least, reverted to its insistence on a non-aggression pact and one-on-one talks, which Washington has ruled out.

"It is the stand of the DPRK (North Korea) that the bilateral talks should be held between the DPRK and the US to be followed by the US-proposed multilateral talks in order to settle the nuclear issue between Pyongyang and Washington," Pyongyang's official Korean Central News Agency said.

The dispatch dismissed as "unacceptable" Washington's demand that North Korea scrap its nuclear weapons ambitions prior to substantive dialogue and reiterated North Korea's own demand for a non-aggression pact.

The nuclear crisis was triggered in October when Washington revealed that Pyongyang was running a nuclear programme in violation of a 1994 arms control accord.

North Korea kicked out UN nuclear inspectors late last year and then withdrew from the Nuclear Non-Proliferation Treaty. It has since claimed it has reprocessed 8,000 spent nuclear fuel rods after reopening its nuclear complex at Yongbyon, north of Pyongyang, frozen under the 1994 accord.

WAR.WIRE