The United States is to send a top envoy to east Asia later this week, the State Department said yesterday, as efforts mounted to restart stalled nuclear talks with North Korea.

On a week-long visit, Deputy Secretary of State James Steinberg will visit Vietnam, Malaysia, China, South Korea and Japan from Sept 25 to Oct 1, spokesman Ian Kelly said.

Steinberg is to "exchange views with senior level officials on a wide range of bilateral, regional and global issues," in a trip set to be dominated by talk of North Korea's nuclear program.

His visit comes as Japan's recently elected government, led by Prime Minister Yukio Hatoyama, vowed to maintain the country's hardline stance against North Korea.

Steinberg visited the region in June, just weeks after the reclusive Stalinist state conducted a nuclear test on May 25 and after it bolted from six-country nuclear talks.

North Korea has since offered to resume talks, a move welcomed by the United States.

"The ultimate goal... (is the) denuclearization of the Korean peninsula a commitment to the six-party talks as the best mechanism to attain that," Kelly said on Wednesday.

Obama warns North Korea and Iran

Earlier in the day US President Barack Obama, in his maiden speech to the UN General Assembly, said North Korea and Iran threatened to take the world down a "dangerous slope."

"If the governments of Iran and North Korea choose to ignore international standards, if they put the pursuit of nuclear weapons ahead of regional stability and the security and opportunity of their own people, if they are oblivious to the dangers of escalating nuclear arms races in both East Asia and the Middle East - then they must be held accountable," he said.

North Korea quit six-nation talks aimed at ending its nuclear program - which bring together the two Koreas, China, Japan, Russia and the United States - in April after the United Nations censured its long-range rocket test.