"The US is staging adventurous joint military exercises as preparations for a pre-emptive strike on the DPRK (North Korea) in order to achieve its dark scheme in Northeast Asia," a foreign ministry spokesman said.

"We cannot but have doubts whether the US is willing to change its hostile policy against our republic," he said in a Korean-language statement carried in the North's state media.

The 12-day drill to start on August 18 is the biggest joint military exercise between South Korea and the United States, which have maintained a mutual defense pact since the 1950-1953 Korean War. Some 37,000 US troops are stationed in South Korea.

The exercise will focus on computerized war games involving South Korean troops and US forces based in and out of the peninsula.

The North's spokesman urged Washington not to irritate its "dialogue partner" ahead of the six-party talks on its nuclear standoff with the United States which will also involve South Korea, Russia, Japan and China.

Pyongyang claims Washington is intent on launching an invasion to overthrow its communist regime and has insisted that the United States offer security guarantees to address the nuclear issue.

US President George W. Bush has said Washington had no intention of attacking the Stalinist state and has promised significant US and international help once the North scraps its nuclear weapons drive.

North Korea has said the six-way talks would take place in Beijing, but details and timing of the talks are still being discussed.

Japan's Yomiuri Shimbun said Thursday that North Korea wants to hold the talks in the first week of September while host China has proposed an August 21 or 25 start.

The United States hopes to hold them in August ahead of a UN general assembly meeting in New York in September, it said.

The Japanese daily said North Korea has been contacting participating nations directly without consulting China, Pyongyang's closest ally.

North Korea has grown frustrated with China, which sided with the US position by demanding the Stalinist regime give up its nuclear weapons while acting as a mediator between Pyongyang and Washington, it said.

The nuclear crisis erupted in October when Washington accused the Stalinist state of reneging on a 1994 bilateral nuclear freeze accord by setting up a clandestine atomic program based on enriched uranium.

North Korea then kicked out International Atomic Energy Agencymonitors and withdrew from the treaty.

Pyongyang has since claimed to have reprocessed 8,000 spent nuclear fuel rods at its nuclear plant at Yongbyon.

Washington believes North Korea had extracted enough weapons-grade plutonium for about two nuclear bombs before it froze its Yongbyon plant. Reprocessing the fuel rods could provide enough additional material for around six bombs within months, according to analysts.

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