Snow, briefing reporters one day before US President George W. Bush and South Korean President Roh Moo-hyun were to meet here, said it was up to North Korea whether stalled six-country talks resume for that purpose.

"The North Koreans need to come back to the table," said Snow. "The United States has worked with its allies and made clear to the North Koreans that they have obligations."

South Korea has been pressing the United States to show greater flexibility in efforts to restart the six-party nuclear disarmament talks, which also include Russia, China and Japan.

"There are incentives awaiting the government if it behaves well. That remains the proper approach. And it also remains the proper approach to say to those in the neighborhood, 'You're closest; you have the most influence; you need to step up as well.'"

At a meeting last September, the impoverished North agreed in principle to give up its nuclear weapons program in exchange for aid and security and diplomatic guarantees.

But Pyongyang boycotted the talks two months later to protest US sanctions on a Macau-based bank accused of laundering and counterfeiting money for the North.

In July, it test-fired seven missiles, sparking condemnation from the UN Security Council which imposed sanctions related to the missile programme.

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