Top U.S. and North Korean nuclear envoys are expected to discuss the North's past abductions of Japanese nationals in bilateral talks in Beijing from Tuesday.

A well-informed source on the North's nuclear program said Sunday that the envoys are expected to have "deep discussions" about the abductions.

The source said the kidnappings are known to be part of the talks' agenda as the Bush administration and U.S. lawmakers are urging progress on the issue before Washington removes Pyongyang from the U.S. list of terrorism-sponsoring states.

In a meeting with chief nuclear negotiators from South Korea, Japan and the United States in Washington last week, Japan was reportedly negative toward the delisting of the North from the terrorism list, citing the kidnappings.