SEOUL, South Korea — A North Korean official told visiting Japanese scholars in Pyongyang last week that a nuclear test was an "indispensable" step toward proving the nation's military capabilities to the world and suggested his government might conduct one soon, the head of the Japanese delegation said.

Word that North Korea is considering a nuclear test came as the government appeared to hint late Sunday it was willing to return, under certain conditions, to six-party negotiations aimed at its nuclear disarmament that have been stalled for 11 months.

During those talks, North Korea had suggested it might conduct a test. But last week's statement was the first mention by a North Korean official about a test since recent intelligence reports warning of such a possibility.

Yasuhiko Yoshida, a former U.N. proliferation expert who led the delegation, said he held two discussions last Tuesday with officials at the North Korean Foreign Ministry's Institute for Disarmament and Peace.

Yoshida said the comment about testing came during the second discussion, in an unarranged phone call placed by the institute's deputy director, Pak Hyon Jae. According to Yoshida, Pak said a North Korean nuclear test was "indispensable," adding, "you'll find that out soon."

"It is important that this official at a government think tank admitted that nuclear testing was necessary," said Yoshida, a noted North Korea specialist at Osaka University of Economics and Law. He led a humanitarian medical mission to Pyongyang, the North Korean capital.

U.S. officials have said spy satellite photos indicate North Korea could be preparing for a nuclear test at a site in the northeast of the country, although they cautioned the activity could be a ruse.

Officials of Asian nations are trying to find a way to jump-start the six-nation talks, which involve North and South Korea, China, Japan, Russia and the United States. Some Asian diplomats say they fear the talks will never resume.

The leaders of China and South Korea — North Korea's two largest trading partners — issued a joint statement in Moscow yesterday calling on North Korea to return to the table.

The country declared itself a nuclear power in February and vowed to stay away from the talks, citing the Bush administration's "hostile policy." But Sunday, it hinted it may yet be willing to resume the talks.

A spokesman for the Foreign Ministry said North Korea wanted to meet with U.S. officials to confirm reports in South Korea that Washington was ready to recognize the North as a "sovereign state."

The spokesman, quoted by the official KCNA news agency, also called for bilateral negotiations but indicated they could take place during a resumption of the six-nation talks.

North Korea has repeatedly demanded one-on-one talks with Washington, but the Bush administration has steadfastly refused. Raising the possibility of bilateral negotiations within the framework of the multilateral talks is thought to be more palatable to the White House.

According to The Associated Press, former chief U.N. weapons inspector Hans Blix said yesterday that because of its own nuclear moves, the Bush administration has only "muted" support in much of the world in its effort to condemn and shut the North Korean and Iranian nuclear programs.

Blix also cited positions taken by Undersecretary of State John Bolton devaluing treaties and international law.

"There is a feeling the common edifice of the international community is being dismantled," the Swedish arms expert said.

Iran acknowledges uranium processing

TEHRAN, Iran — Iran confirmed yesterday it converted 37 tons of raw uranium into gas, its first acknowledgment of advances made in the production of enriched uranium before it formally suspended nuclear activity in November under international pressure.

The announcement means Tehran is in a position to quickly start enriching uranium if it lifts the suspension. It comes as European negotiators are trying to seal an agreement to ensure Iran's nuclear program does not produce weapons.

Enriched uranium is useful in the generation of electricity, which is permitted under the Nuclear Non-Proliferation Treaty, but it also can be turned into nuclear weapons. Iran insists its program has only peaceful purposes, while the U.S. says Tehran wants to obtain atomic arms.

Iran processed the uranium ore concentrate into UF-4 gas before halting enrichment-related activities, said Mohammad Saeedi, deputy head of the Atomic Energy Organization of Iran. If processed further into UF-6 gas, the material could be fed into centrifuges and enriched.

"We converted all the 37 tons of uranium concentrate known as yellowcake into UF-4 at the Isfahan Uranium Conversion Facility before we suspended work there," Saeedi said.

France, Britain and Germany, which are negotiating on behalf of the European Union, had agreed in talks ahead of the November suspension that the Islamic Republic could finish processing the 37 tons of raw uranium into gas.