China on Monday slammed North Korea for carrying out a nuclear test, openly criticizing its ally's nuclear program for the first time and demanding that Pyongyang return to disarmament talks.

"China expresses its resolute opposition," the Chinese Foreign Ministry said on its Web site. It said the North "defied the universal opposition of international society and flagrantly conducted the nuclear test."

CountryWatch: North Korea | South Korea | China

The statement, also read on state TV during the midday national news, did not mention possible sanctions. But it was the most strongly worded Chinese reaction to date to the North's nuclear program and dropped the conciliatory tone of Beijing's previous statements.

Raw Data: North Korean Statement on Alleged Nuke Test

Foreign Minister Li Zhaoxing talked by phone with U.S. Secretary of State Condoleezza Rice after the test and affirmed Beijing's stance, a separate statement on the ministry Web site said. It said they "exchanged views on the new development in the situation on the Korean Peninsula" but did not give any other details of the conversation.

Pyongyang's decision to go ahead with the test was a diplomatic disaster for Beijing, which had set aside its usual reluctance to get involved in international affairs, taking the lead in organizing disarmament talks.

China's Foreign Ministry publicly appealed to the North Korean government last week to show restraint after its announcement of the planned test.

"China strongly demands that North Korea abide by its non-nuclear pledge and avoid any other actions that further worsen the situation, and return to the track of the six-party talks," according to the Chinese statement issued Monday.

It appealed to all governments in the nuclear dispute to stay calm and pursue a negotiated settlement.

The Chinese-organized talks have been stalled since late 2005 over Pyongyang's opposition to U.S. financial sanctions imposed on North Korean companies accused of counterfeiting and other offenses.

Other participants are the United States, South Korea, Japan and Russia.

Beijing is the impoverished North's main source of food and fuel aid, and is under intense U.S. pressure to use its leverage to get Pyongyang to return to the talks.

But analysts say Beijing is reluctant to push the North too hard for fear of causing leader Kim's regime to collapse, sending a flood of refugees into China and upsetting the region's military balance.

In July, Kim's government also defied Chinese appeals when it test-fired missiles.