A top North Korean nuclear envoy will visit the United States for rare bilateral talks next month, a news report said Friday as diplomats pushed to revive negotiations on ending Pyongyang's nuclear program.

Plans call for North Korea's Kim Kye Gwan to travel to the U.S. in March, South Korea's Yonhap news agency reported from Beijing, citing an unidentified source. In Washington, State Department spokesman Fred Lash said late Thursday that he had not seen the report.

U.N. political chief, B. Lynn Pascoe, said after concluding a four-day trip to North Korea on Friday that he was unaware of plans for Kim to travel to the U.S.

North Korea, believed to have enough weaponized plutonium for at least half a dozen atomic bombs, walked away from disarmament-for-aid negotiations last year during a standoff over its nuclear and missile programs.

However, after tightened sanctions and financial isolation, the impoverished nation has reached out to Washington, Seoul and Beijing in recent months.

Pascoe, the highest-ranking U.N. diplomat to visit North Korea since 2004, said he met with North Korea's president and foreign minister and "argued strongly that the six-party talks should be resumed without preconditions or further delay."

However, the North Korean side did not seem prepared to immediately return to the international disarmament talks, he said.

"The attitude right now as I said is that certainly they were not happy with the sanctions and they were certainly not eager, not ruling out but not eager, to return to the six-party talks," said Pascoe.

Pascoe said he was reluctant to describe the North Korean position in any more detail because the U.N. is not directly involved with the negotiations.

The disarmament talks involve the two Koreas, the U.S., Japan, Russia and host China.

A bilateral meeting between the North Korean envoy and U.S. officials would be a strong sign that the push to get the disarmament talks back on track was gaining traction. It would also confirm a warming in relations between the U.S. and North Korea, wartime rivals that do not have diplomatic relations.

Earlier, spokesman P.J. Crowley said U.S. officials haven't ruled out future meetings with the North Koreans, but "we believe firmly that the next meeting that U.S. representatives and others should have with North Korea is through a formal six-party meeting."

North Korea wants sanctions eased and a peace treaty with the U.S. formally ending the 1950-53 Korean War if it returns to the six-party talks. Seoul, Tokyo and Washington have all urged Pyongyang to return to the disarmament talks and show progress on denuclearization before any discussions on a peace treaty or sanctions.