North Korea (search) said Wednesday it would give up its nuclear weapons only after the alleged U.S. atomic threat is removed from the divided peninsula and relations with the United States are normalized, according to a South Korean report.

The North also demanded the United States abandon plans to topple its communist government and instead establish mechanisms for peaceful coexistence, according to a report from South Korea's Yonhap news agency, guarantees for its longtime ally. The official, who spoke on condition of anonymity, declined to go into specifics about Pyongyang's demands.

Both Washington and Seoul deny there are any U.S. nuclear weapons in the South, and South Korea earlier raised the possibility of opening South Korean and U.S. bases for some form of verification of that fact by the North.

North Korea also said Wednesday it was hard to accept a U.S. proposal made at the last round of arms talks in June 2004, calling it unreasonable and lacking in details about ending the U.S. nuclear threat and for peaceful coexistence of the countries.

Under that plan, Washington was to give the North three months to freeze its programs and prepare for disarmament.

Meanwhile, U.S. Assistant Secretary of State Christopher Hill (search) called on the North at the talks to dismantle its nuclear weapons, according to the Yonhap report. He also said the countries at the talks should deal with other issues, such as missiles and human rights.

A U.S. Embassy spokeswoman said she couldn't confirm the report.

Hill said Tuesday evening after his second meeting in as many days with the North Koreans that they expressed concerns about the "sequencing" of proposals. "They do not want to have obligations ahead of other people's obligations," he said.

Earlier Tuesday at the talks' opening, Hill repeated Washington's assurances to the North that it has no intention to use force to resolve the crisis.

The fourth round of arms talks — which include China, Japan, Russia, the United States and the two Koreas — reconvened Tuesday after a 13-month gap. North Korea had boycotted the talks since June 2004, citing what it called "hostile" U.S. policies.

China's chief delegate, Wu Dawei, called on all sides at the start of Wednesday's session to "seize opportunities, meet challenges and work together with their utmost political courage to create a better future for Northeast Asia," the official Xinhua News Agency reported.

In Washington, State Department spokesman Sean McCormack said Tuesday that developments would be gradual and that it would be progress for all parties to agree to another round of talks.

Delegates have tried to show their commitment to progress by setting no end date for the talks, unlike earlier rounds that lasted only several days.

The latest nuclear standoff with North Korea erupted in late 2002, when U.S. officials accused the country of running a secret uranium enrichment program.

Since then, the North has pulled out of the Nuclear Nonproliferation Treaty and taken steps that would let it harvest more radioactive material for bombs from its publicly acknowledged plutonium program.

In February, the North publicly claimed it had nuclear weapons, which many experts believe to be the case despite a lack of any known nuclear tests that would confirm its arsenal.