A nuclear test by North Korea ahead of a US presidential election could deal a severe blow to President George W. Bush's strategy of diplomatic containment of the Stalinist state that has openly bragged about its nuclear ambitions.

The president has stated repeatedly that six-party talks involving all of North Korea's neighbors in addition to the United States is an effective tool for keeping these ambitions in check.

But he has been under fire from Democratic presidential candidate John Kerry, an advocate of direct negotiations with Pyongyang.

The officials declined to describe to AFP the information that prompted the intense debate, of which the White House has been made aware.

But one of them described it as serious enough to generate concern.

"It is well known and has been widely reported that North Korea's nuclear capability is a concern to us," the official said, speaking on condition of anonymity.

The New York Times will report in its Sunday edition that US intelligence picked up suspicious movement of materials around several locations deep inside North Korea that US analysts believe could eventually become nuclear test sites.

The suspicious activities involve one location where possible conventional components of a nuclear bomb were tested last year, according to the report.

But top analysts at US intelligence agencies differ on how to interpret the activities, primarily because they have not detected electrical cables leading into an underground test shaft, a telltale sign of preparations for a nuclear blast.

While confirming the internal discussions, another official described the debates as mainly "speculation," adding: "I can't substantiate the claims."

Officials do not discount the possibility of diplomatic brinkmanship on the part of the mercurial North ahead of the next round of six-party talks between the two Koreas, Japan, China, Russia and the United States set for later this month.

Pyongyang has hinted the talks could be jeopardized by South Korea's recent admission that its scientists carried out nuclear experiments.

British and Chinese officials were in Pyongyang on Saturday in a bid to salvage the talks.

The US Central intelligence Agency believes North Korea already has one or two, or maybe more nuclear weapons.

Its 8,000 fuel rods that North Korean officials say are now being reprocessed at the Yongbyon nuclear plant could generate enough plutonium for four or six more nuclear weapons, according to the US Congressional Research Service.

Two larger nuclear reactors, the service said, are being built in Yongbyon and Taechon. If completed, their plants would be capable of producing enough spent fuel to produce 200 kilograms of plutonium annually, which would be enough to manufacture nearly 30 atomic bombs a year.

In addition, North Korea is reported to have a secret uranium enrichment program that could deliver two nuclear bombs annually beginning in 2005.

The country, whose uranium deposits are estimated at 26 million tonnes, is believed to have one uranium producing mine, the CRS reported.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.