Beijing ? North Korea wants promised energy aid and removal from U.S. terrorism and sanctions blacklists before it will provide a complete declaration of its nuclear programs, American researchers said Saturday after a trip to the North.

North Korean officials also said they slowed the removal of fuel rods from the country’s Yongbyon reactor because the United States and other nations have fallen behind in supplying aid under an Oct. 3 disarmament pact, said Siegfried Hecker, a Stanford University physicist, and Joel Wit, a former State Department expert on the North.

Hecker and Wit said they visited Yongbyon and met with top foreign affairs officials and those in charge of the nuclear program but declined to disclose their names. Also traveling with them was Keith Luce, a staff member for Sen. Richard Lugar, an Indiana Republic.

The October deal calls for the North to disable its nuclear facilities and fully declare its nuclear programs in exchange for energy aid and political concessions, including removal from the U.S. terrorism list by the end of 2007.