Nam Sung-Wook, a North Korea expert at Korea University who advises President-elect Lee Myung-Bak, said he expects Pyongyang to stall on the disarmament deal after missing a year-end deadline.

"National Defence Commission Chairman Kim Jong-Il seems not to have made a decision yet to abandon nuclear weapons," Nam told SBS radio.

Pyongyang will "drag its feet in negotiations with the US over what it can get in return, probably until late February," he added.

Lee, who has promised a firmer line with North Korea, takes office on February 25.

The following day, in what Nam described as an "unprecedentedly friendly event" between the two countries, the New York Philharmonic is to perform in Pyongyang.

Nam declined to elaborate to AFP on his remarks.

Under a landmark six-nation agreement the North was supposed to have disabled its main atomic plants and declared all its nuclear programmes by December 31, in return for one million tons of fuel oil or equivalent energy aid and diplomatic benefits.

But the year-end deadline slipped, with the North yet to complete the disabling work and no signs of an upcoming declaration.

The United States, Japan and South Korea -- members of the negotiations along with Russia, China and the North itself -- expressed disappointment at the missed deadline.

President-elect Lee, of the conservative opposition Grand National Party, says he will link future aid to North Korea more closely to progress in nuclear disarmament.

Nam described the communist state's New Year policy message as "positive" in that it lacked its usual criticism of Lee's party.