WASHINGTON - THE United States launched a new diplomatic push on Tuesday to obtain a long-sought cornerstone to scrapping North Korea's atomic arms by sending key envoys this week to Pyongyang and nearby capitals.

The State Department said its Korea office director Sung Kim was due on Thursday in the North Korean capital while Deputy Secretary of State John Negroponte will leave on Wednesday for Tokyo, Seoul and Beijing.

It said the visits are part of six-party negotiations to obtain a full declaration from North Korea on its nuclear activities but was circumspect when asked if it could be in hand and verified before the end of the month.

The North, which staged a nuclear test in October 2006, is disabling its plutonium-producing reactor and other plants under a deal reached last year with the United States, China, Japan, Russia and South Korea.

But disputes over the declaration due on Dec 31 have blocked the start of the final phase of the disarmament process - the dismantling of the plants and the handover of all material.

The declaration is key to the disarmament negotiations as it would serve as a baseline on which to account for dismantled material.

In return for total denuclearisation, the impoverished Stalinist state would receive energy aid, a lifting of US sanctions, the establishment of diplomatic relations with Washington and a formal peace treaty.

Syria nuclear plant
In addition to the declared plutonium bomb-making operation, the US said the declaration must clear up suspicions about an alleged secret uranium enrichment programme and about suspected involvement in building a nuclear plant in Syria.

The North denies both activities. Under a reported deal, it will merely 'acknowledge' US concerns about the two issues in a confidential separate document to Washington.

The envoys are making their first trips to the region since Washington two weeks ago detailed allegations that North Korea had helped Syria build the reactor, which Israeli warplanes destroyed in a raid last September.

Mr Robert Einhorn, a former US government non-proliferation chief who worked on North Korea, said he expected the envoys to focus on obtaining detailed records for the Yongbyon plutonium reactor to support the declaration.

Mr Einhorn said US President George W. Bush's administration appears ready 'to live with North Korea's reluctance to be fully explicit' on proliferation and uranium enrichment but believed it 'will not close the books' on the subjects.

He said it is taking such an approach because intelligence indicates that North Korea has no active uranium enrichment programme and that its sole proliferation programme was destroyed in the Israeli raid.

But Mr Einhorn said Washington fears Pyongyang has not been fully open with its denial that disgraced Pakistani nuclear scientist AQ Khan transferred centrifuges, which enrich uranium, to North Korea.

Mr McCormack said Mr Negroponte will also discuss other 'significant regional bilateral issues' with officials in Japan, South Korea and China during his tour that ends on May 12.

State Department press officer Nancy Beck said the diplomatic push comes as 'a team of US experts is currently in Pyongyang to continue discussions' on providing food aid to deal with 'significant food shortages.' But she told reporters the discussions 'remain inconclusive.'

The provision of food aid depends on the level of need, supply 'and our view of other needs that might exist, and our ability to ensure aid is reliably reaching the people in need,' Ms Beck told reporters.