Actor Paul Newman told friends as far back as 18 months ago that he was battling cancer but has remained energetic and active in charity work, a friend and business associate said yesterday.

Writer A.E. Hotchner, who co-founded Newman’s Own food products with the actor, said Newman, 83, was doing fine as of two weeks ago. Asked if Newman had cancer, Hotchner said “he made it known to a lot of his friends.”

Hotchner, who lives near Newman and his wife, actress Joanne Woodward, in Westport, Conn., said he did not know what type of cancer Newman had because “I don’t believe it’s any of my business, and I don’t want to get into it.”

The widely acclaimed actor of films such as The Color Of Money and The Sting Tuesday responded to a flurry of unconfirmed media reports that he was gravely ill with cancer by issuing a terse statement saying he was “doing nicely.”

His Los Angeles-based spokesman Jeff Sanderson declined to elaborate and yesterday was not immediately available to comment.

According to numerous reports, Newman has been diagnosed with lung cancer and was undergoing outpatient treatment at Memorial Sloan-Kettering Cancer Center in New York. A spokeswoman for Sloan-Kettering has said she had no information about whether Newman was a patient there.