Trying to stop a process that US intelligence is convinced already has produced one or two bombs, a State Department spokesman offered direct talks if North Korea ends its boycott of six-party negotiations.

In the past, the US has held discussions with North Korean officials against the backdrop of the six-party talks, department spokesman Tom Casey said.

"And if the North Koreans were to return to the talks, we would certainly continue that practice [of direct discussions with Pyongyang]," he added. 

The statement came in response to one by a North Korean Foreign Ministry spokesman that seemed to soften Pyongyang's demand for direct dealings with the Bush administration.

According to the official North Korean Central News Agency, the spokesman said Pyongyang had not called for direct talks with the US to be separate from the six-party negotiations.

No nuclear test

Meanwhile, North Korea on Tuesday dismissed reports that it was preparing a nuclear test, calling them US propaganda, and blamed Washington for the impasse in international talks to disarm the state.

"The United States is making noise, saying that our country will have an underground nuclear test in June and it will notify the International Atomic Energy Agency, Japan and other related countries," the North's main state-run Rodong Sinmun daily wrote in a commentary, according to the country's official Central News Agency.

US officials said last week that spy satellites showed possible preparations for North Korea's first-ever nuclear weapons test, including the digging and refilling of a large hole at a suspected test site in northeastern Kilju, along with the apparent construction of a reviewing stand being erected some distance away.

The Washington Post also said on Tuesday that a North Korean official told a Japanese scholar visiting Pyongyang that a nuclear test was indispensable to prove North Korea's capabilities, and suggested it might take place soon.

International Atomic Energy Agency chief Mohamed ElBaradei said on Sunday that North Korea had plutonium that could be converted into five or six nuclear weapons.