As the United States and China renew their calls for North Korea to return to nuclear talks, Pyongyang is stepping up its rhetoric and pledging to defy any pressure for it to disarm.

Throughout the North Korean nuclear crisis, Pyongyang has resorted to defiant and often insulting language against the United States and its leaders.

Tuesday, a state-run newspaper in Pyongyang accused Washington of "making a fuss" over speculation that the North may be planning a nuclear test soon.

Along with what has become a usual list of personal attacks against President Bush, the commentary repeated Pyongyang's earlier assertions that it would not deal further with his administration.

Referring to the possibility that the United States might refer the case of Pyongyang's nuclear weapons to the U.N. Security Council, the commentary declared that North Korea's "bold stance" is to let the United States do what it wants.

China, the host of three unsuccessful rounds of talks on Pyongyang's nuclear weapons program expressed its growing concern over the reports of a possible nuclear test. Chinese Foreign Ministry spokesman Liu Jianchao said Beijing remains committed to pursuing a diplomatic solution.

"We believe the appearance of nuclear weapons in North Korea is not beneficial for any country in the region and the world," he said. "That is why it is necessary for us to be genuinely committed to denuclearization."

President Bush and his aides have called North Korean leader Kim Jong Il a "tyrant" and referred to the country as "an outpost of tyranny."

In Beijing, the Chinese spokesman suggested that those involved in the talks should not "say or do anything that is not in favor of continuing the six-party talks." The talks have been stalled since North Korea refused to attend a fourth round in September, accusing the United States of taking a "hostile" attitude toward Pyongyang.

North Korea says it has nuclear weapons, and western and Asian experts agree the country may well possess several nuclear devices.

Adding to concerns about a possible nuclear test were reports this week from a delegation of Japanese scholars recently back from North Korea. The head of the delegation was quoted as saying North Korean officials told him a test is an "indispensable" step toward proving Pyongyang's nuclear capabilities.

Secretary of State Condoleezza Rice on Monday repeated Washington's calls for Pyongyang to return to the six-way talks, saying they are the "best route." She said anything the North Koreans do to escalate the situation would only isolate their country further.