The Bush administration blamed China yesterday for not doing enough to cajole North Korea back to nuclear talks but gave no indication it is willing to revise its own strategy, which has so far failed to roll back the North's advancing nuclear program.

Instead, the White House called on North Korea to set a date for a new round of regional talks, even as North and South Korean officials were unable to agree yesterday on whether the negotiations would take place at all.

U.S. officials said Secretary of State Condoleezza Rice might return to Asia next month for more meetings with allies aimed at resolving an impasse over the future of the talks and North Korea's nuclear program.

Rice visited Asia in March in an effort to persuade China and South Korea to increase pressure on Pyongyang. But the two U.S. allies have been reluctant to squeeze an impoverished and unpredictable nation, the size of whose true nuclear arsenal is unknown. Pyongyang announced in February that it has nuclear weapons, though the assertion has not been verified by intelligence services.

After months of speculation that North Korea might be preparing a nuclear test, the reclusive nation indicated last week that it would be willing to come back to the talks, and eventually disarm, if Washington treated it with respect and as an equal partner in the negotiations.

White House spokesman Scott McClellan responded yesterday by saying that "North Korea needs to commit to a date for returning to the six-party talks without precondition, and be ready to talk in a serious way about how to move forward."

President Bush refuses to negotiate directly with North Korea or offer incentives to an authoritarian state that is developing nuclear weapons. Instead, the president has said the issue should be addressed in regional talks, together with China, South Korea, Japan and Russia.

But the talks have yielded few results and have been on hold for a year. At the same time, North Korea is believed to have made significant nuclear advances. The intelligence community now believes it has the ability to make as many as eight nuclear devices.

Undersecretary of State Robert Joseph, who recently replaced John R. Bolton as the administration's top nuclear nonproliferation official, told reporters yesterday that the Bush administration's approach will continue and that he is hopeful the North Koreans "are going to come back" to the talks.

But he said China, which is a close ally of North Korea and which supplies the impoverished state with oil and food, needs to do more to get Pyongyang back into the negotiations.

"The Chinese can exert more influence," he said. "China has to make a decision how to influence North Korea. It has a number of tools."

The Washington Post reported last month that Chinese officials rejected U.S. suggestions that they cut off North Korea's supply of oil as a way of pressuring it to return to the disarmament talks.

Joseph would not comment on the report, but he said that if China does not take more action "there possibly could be very significant consequences for U.S.-Chinese relations." He would not discuss specifics and emphasized the importance of the two countries' working relationship and shared goals.

"As you look at alternative futures, the best future for China is a future in which there are no nuclear weapons on the Korean Peninsula."

The Bush administration has not said what it would do if the talks were abandoned, and its options are unclear.

China has refused to discuss North Korea's nuclear program in the U.N. Security Council, which has the authority to impose sanctions and embargoes. The matter was referred to the council two years ago, when North Korea expelled U.N. inspectors and removed seals from fuel rods and nuclear equipment.

The Wall Street Journal reported yesterday that the White House is planning to pursue the assets of companies that are believed to be aiding the weapons or nuclear programs in North Korea, Iran and Syria.