NEW YORK • "You may say I am a dreamer/But I am not the only one," John Lennon sang in Imagine.

His wife Yoko Lennon must have felt the same way for she has now been credited as a co-writer for the 1971 hit song.

At the annual meeting of the National Music Publishers Association in the United States on Wednesday, the pair were lauded with its Centennial Song award for Imagine.

At the ceremony, a video from 1980 was screened, in which Lennon said the track "should be credited as a Lennon-Ono song because a lot of it - the lyrics and the concept - came from Yoko".

"But those days I was a bit more selfish, a bit more macho, and I sort of omitted to mention her contribution. But it was right out of Grapefruit, her book... There's a whole pile of pieces about 'Imagine this' and 'Imagine that'," he revealed.

According to trade publication Variety, the association's chief executive David Israelite noted that the Ono decision could encounter some resistance.

A song enters the public domain 70 years after its creator's (or creators') death. Ono is still alive, thus significantly extending the number of years that the song will churn out income for its writers.

At the ceremony in New York, Ono, 84, went on stage to accept the award. She was in a wheelchair, pushed by her son Sean.

She said her illness - she is suffering from an unclear flu-like ailment - has made her appreciate the song and other facets of life more fully.

Veteran punk rocker Patti Smith then amped up the nostalgia factor by performing Imagine, with her daughter Jessie joining her on the piano.