"The United States can never evade its responsibility for the abortion of the next round of the six-party talks," the North's ruling party newspaper Rodong Sinmun said in a commentary.

"It is none other than the US which has demolished the very foundation of the six-party talks."

The daily urged Washington to take practical steps to restore "the already demolished basic foundation" of six-party talks involving the two Koreas, Japan, China, Russia and the United States.

The six nations have held three rounds of talks on ways to curb the North's nuclear weapons drive in return for diplomatic concessions and possible economic aid.

A fourth round was scheduled for this month but Pyongyang has refused to return to the negotiating table.

The North hardened its position after the South disclosed its own past experiments, which it says were for resaerch purposes only.

In a commentary Monday, the North's KCNA news agency said Pyongyang cannot discuss resuming the six-party talks and renouncing its "nuclear deterrent force" unless Washington drops its double standards and hostile policy.

"As is already known well, the groundwork of the talks collapsed due to the deliberate provocation of the US hardline conservatives and the double standards applied by them in dealing with the nuclear issue," the agency said.

The dispute over North Korea's nuclear ambitions flared in October 2002 when Washington accused Pyongyang of operating a nuclear weapons program based on enriched uranium in violation of a 1994 agreement.

Pyongyang has denied running the uranium-based program but has restarted its plutonium program.