The US team handling North Korea will head this week for talks in China, Japan and South Korea in the wake of Pyongyang's boast of progress on uranium production, the State Department said Monday.

Glyn Davies, the US special representative on North Korea policy, and Clifford Hart, the envoy for moribund six-nation nuclear talks, will leave Tuesday on their first trip to the region since taking their jobs in October.

Starting their three-capital trip in Seoul, the envoys "will meet with senior government officials to exchange views on Korean Peninsula issues," the State Department said in a statement.

The United States in October held rare one-on-one talks with North Korea in Geneva, hoping to maintain channels of communication despite pessimism in Washington at reaching a solution on long-running disputes with Pyongyang.

North Korea -- which has defied the world by testing two atom bombs -- last week said it is making rapid progress on enriching uranium and is building a new reactor, projects that could give it a second way to make nuclear weapons.

"We view those kinds of statements as unconstructive. We would call on North Korea, as we've done many times, to live up to its commitment in the 2005 joint statement," State Department spokesman Mark Toner told reporters.

North Korea agreed in six-nation talks in 2005 to give up its nuclear program in return for aid and security guarantees. The United States has also insisted that North Korea repair ties with the South before substantive new negotiations can begin.

US Secretary of State Hillary Clinton, who was visiting South Korea amid the announcement on uranium, called on the North "to take concrete steps that promote peace and stability and denuclearization."

The six-way talks comprise China, Japan, the two Koreas, Russia and the United States.