"When an appropriate time comes, the DPRK's (North Korea's) increased nuclear deterrent force will be proved in practice," said a foreign ministry statement carried by the official Korean Central News Agency (KCNA).

The statement blamed the United States for the year-long nuclear crisis and said it would never disarm -- North Korea's term for scrapping its nuclear weapons -- while the Washington maintained a hostile policy towards it.

On Thursday North Korea's foreign ministry said Pyongyang would display the "physical force" of its nuclear deterrent, an apparent threat to test a nuclear device.

The United States believes Pyongyang has one or two nuclear weapons but evidence is scant and some officials believe that North Korea's repeated boast in recent weeks about its nuclear deterrent is no more than bluster.

South Korean officials said Thursday's statement appeared to be brinkmanship. North Korea often makes inflammatory statements in order to gain the upper hand in negotiations with the United States.

Efforts are currently under way to jump-start a second round of six-nation talks on the nuclear crisis.

The two Koreas, China, Japan, Russia and the United States met late August in Beijing to ease tensions caused by the stand-off over North Korea's nuclear weapons drive.

But the talks ended inconclusively with no date set for the next round, as North Korea later said the meeting was "useless" and it had no interest in further talks, preferring instead to build up its nuclear deterrent.

In the ensuing weeks Pyongyang has raised the stakes by claiming it is making atomic bombs after reprocessing spent fuel rods, and has imposed further obstacles to a new round of negotiations by demanding that Japan be excluded.

North Korea demands a legally binding non-aggression pact from the United States as a first step before responding to Washington's demand for a complete and verifiable dismantling of its nuclear weapons drive.

Pyongyang claims the United States is planning to attack the Stalinist country despite frequent denials from US officials, including President George W. Bush.

"Now it is as clear as noonday that the US is set to seize the DPRK by force, through high-handed actions and by military means," said Saturday's statement, attributed by KCNA to an unidentified foreign ministry spokesman.

"It would be the biggest mistake for the US to calculate that the DPRK would sit idle and disarm itself, taken in by Washington's trick," it said.

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