North Korea's top nuclear envoy arrived in Beijing on Thursday en route to Singapore for meetings with former U.S. diplomats and security experts, a diplomatic source said.

Ri Yong-ho, North Korea's chief negotiator for the long-stalled six-party talks on the North's nuclear weapons program, is expected to meet with former U.S. special envoy for North Korea policy Stephen Bosworth and other American experts on Sunday, the source said on  condition of anonymity.

Other American counterparts would include former deputy U.S. nuclear negotiator Joseph DeTrani and Leon Sigal, director of the Northeast Asia Cooperative Security Project at the Social Science Research Council, according to the source.

Though the U.S. government will not be involved, the upcoming meetings could be a chance for the two sides to better understand each other's position on how to resume the six-party talks that have been on hold since the last session in late 2008.  

Last Saturday, North Korea offered to temporarily suspend nuclear tests in exchange for a halt to joint U.S.-South Korea military exercises, but both Seoul and Washington rejected the proposal.

Relations between the U.S. and the North have worsened further recently following a cyber-attack on entertainment company Sony Pictures. The U.S. has blamed the North for carrying out the attacks and imposed fresh sanctions, but Pyongyang has categorically denied its involvement. (Yonhap)