A diary kept by John Lennon in 1980 until he was shot to death is missing, a close friend of the late rock musician said yesterday.

One source in the search was quoted as saying that the diary could be worth "millions."

The diary was one of five stolen about six months after Lennon was killed Dec. 8, 1980, in front of his Dakota apartment building in New York, where Lennon and his wife, Yoko Ono, lived. Four of the diaries were returned by a former Lennon employe, Fred Seaman, who pleaded guilty last month to stealing them.

But the 1980 volume, which covered Lennon's return to public and professional life via his award-winning album "Double Fantasy," is still missing, according to Elliot Mintz, a longtime friend of Lennon and Ono's.

Both the existence of the diaries and their theft had been kept secret until Seaman's guilty plea.

Mintz also said that "shortly after the disappearance of the diaries, it was brought to Yoko's attention that there were other things of John's that were missing," including an unpublished novel titled, "Skywriting By Word of Mouth," along with "poetry, love letters between John and Yoko, an enormous amount of electronic equipment and clothing articles of John's and Yoko's."

The novel, which Mintz described as "poetic, whimsical, surreal, stream-of-consciousness type pieces," and some of the other items have been recovered.

Seaman had been employed by Lenono, Lennon and Ono's music business, and after an internal investigation pointed to Seaman as prime suspect, "Yoko went directly to the police and filed charges," Mintz said.

Commenting on reports that a photocopy of the diary has turned up, Mintz said he knew of no one who had been offered the volume.

"Any person in possession of that diary would be in possession of stolen property," he said, adding that the diaries were "very special and very personal to Yoko."

Mintz said he didn't know whether there had been an entry for Dec. 8, the night Lennon was shot, "but I know that John did make entries right up until the end."

There are no plans to publish any of the returned diaries at this time, Mintz said. Shortly after Lennon's death, Ono was besieged with offers from publishers for her autobiography.

"She kept her own journal," Mintz said from his California home, "but Yoko is not as methodical about journals and diaries as John was. Now she's just trying to get on with her life and be the best possible mother that she can be to Sean. For anyone to have stolen these items just compounds the tragedy that she's already endured."