Two U.S. lawmakers have traveled to North Korea to encourage officials in Pyongyang to stop delaying their return to negotiations on nuclear disarmament.

The two congressmen, Tom Lantos and Jim Leach, spoke to reporters in Beijing Tuesday before boarding an airplane for the North Korean capital.

Mr. Lantos said he is optimistic the ongoing six-nation disarmament talks will succeed, despite the North's announcement that it would delay returning to the table until two weeks later than scheduled.

"We are headed to Pyongyang to attempt to clarify the remaining problems and urge the North Korean government to return to talks in two weeks with a very positive outlook and approach," he said.

The fourth round of multi-party negotiations held since 2003 recessed three weeks ago and was supposed to resume this week. However, North Korea announced Monday it would not return to talks until after the conclusion of ongoing joint military exercises between the United States and South Korea.

Congressman Leach said North Korea should stop stalling and work with other nations in the process to reach an agreement quickly.

"It strikes me the delay does not serve well the North Korean people and of all the parties that should be wanting to move with rapidity, it should be the DPRK," he added.

China, Japan, Russia, South Korea, and the United States have been pressing North Korea to give up its nuclear weapons programs in exchange for economic and security guarantees.

The last round of talks broke off after 13 days on August 7, with North Korea demanding it be allowed to have a non-military nuclear program. The United States is concerned that Pyongyang may use a civilian nuclear program to manufacture atomic weapons.