The United States circulated a draft UN resolution late Monday calling for tough and immediate sanctions against North Korea after the Communist regime announced it had tested a nuclear weapon.

The move comes as world leaders — including North Korea's longtime supporter China — lined up to condemn the reported nuclear test, with some echoing U.S. calls for the United Nations Security Council to impose sanctions against Pyongyang.

South Koreans watch TV news on Monday showing a file image of a North Korean missile in a parade.
(Ahn Young-joon/Associated Press)

U.S. President George W. Bush called the test provocative, "unacceptable" and a threat to global peace and security. He said the action deserves "an immediate response by the Security Council.

"The transfer of nuclear weapons or material by North Korea to states or non-state entities would be considered a grave threat to the United States," Bush said. "And we would hold North Korea fully accountable for the consequences of such action."

Pak Gil Yon, North Korea's UN ambassador, said the Security Council should congratulate his country instead of passing "useless" resolutions or statements.

North Korea's nuclear test reportedly took place at 10:36 a.m. local time Sunday near the city of Kilju.

According to the Associated Press, the draft resolution proposed a trade ban on military and luxury items, the power to inspect all cargo entering or leaving the country, and freezing assets connected with its weapons programs.

'Dangerous act': Harper

Canadian Prime Minister Stephen Harper called the test an "irresponsible and dangerous act" that seriously undermines both regional peace and stability, and global efforts to halt the spread of nuclear weapons.

He said Canada believes that North Korea's security, economic and political goals are best achieved through the framework of the existing six-party talks to address the North Korean nuclear crisis.

Bush said U.S. officials were still trying to confirm that a nuclear explosion had taken place.

Still, he said, "such a claim itself constitutes a threat to international peace and security. The United States condemns this provocative act."

Japanese Prime Minister Shinzo Abe, in Seoul for a summit with South Korean President Roh Moo-hyun, called for "harsh measures" against Pyongyang and warned of the dawn of a "dangerous nuclear age."

"The development and possession of nuclear weapons by North Korea will in a major way transform the security environment in North Asia and we will be entering a new, dangerous nuclear age," he said.

According to North Korea's official news agency, the reclusive country tested its first nuclear weapon on Sunday.

No radiation reported

The Korean Central News Agency reported that the test was successful and no radiation had leaked from the underground site.

The test "will contribute to defending the peace and stability on the Korean Peninsula and in the area around it," KCNA reported.

The U.S. Geological Survey said it recorded a magnitude-4.2 seismic event in northeastern North Korea. Asian neighbours also said they registered a seismic event, but only Russia said its monitoring services had detected a nuclear explosion.

"It is 100-per-cent [certain] that it was an underground nuclear explosion," said Lt.-Gen. Vladimir Verkhovtsev, head of a Defence Ministry department, according to Russia's ITAR-Tass news agency.

The test took place at 10:36 a.m. local time Sunday (9:36 p.m. ET) near the city of Kilju, according to South Korean defence sources cited by South Korea's Yonhap news agency.

South Korean military on high alert

South Korea, which shares the world's most heavily armed border with the North, said it put its military on high alert.

North Korea has created "a severe situation that threatens stability on the Korean Peninsula and in northeast Asia," South Korean President Roh Moo-hyun told journalists.

He said the test would make it difficult for Seoul to maintain its efforts to strengthen ties with its Communist neighbour.

"This is a warning as well as my prediction," Roh said. "Under this situation, it's difficult for South Korea to maintain engagement policy."

China expresses 'resolute opposition'

News of the test followed a demand from China and Japan on Sunday that the Communist country scrub the test.

North Korea said early last week that it would test an atomic weapon because of "the U.S. extreme threat of a nuclear war."

Following that statement, the UN, U.S. and other countries all asked that it not proceed.

China, a longtime North Korea supporter and host of stalled international talks to persuade the fellow Communist country to give up its nuclear ambitions, strongly condemned the act.

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

North Korea is believed to have enough plutonium for as few as four and as many as about a dozen nuclear bombs. But until Monday's reported action, Pyongyang had never tested a device.

With files from the Associated Press