Yoko Ono has opened up about her desperate days as a starving child in her native Japan after granting officials at an anti-poverty campaign in Tokyo the rights to use her late husband John Lennon's track Imagine as an anthem.

The signature peace tune will provide the soundtrack to WhyHunger's 'Imagine There's No Hunger' campaign ads, and the initiative brought back bad memories for Ono as she attended an event for the charity in Tokyo.

She said, "I remember being hungry and I know it's so difficult to just be hungry. One day I didn't bring a lunchbox (to school). The other kids asked, don't you want to eat? I just said, no, I'm not hungry."

Ono insists her late husband would have approved of the use of Imagine in WhyHunger's campaign, which will help officials offer sustainable farming in 22 countries.

She added, "My husband and I really wanted to do something for the world, especially for the children. Children have pride, too, so they don't beg you, but they are in pain and they are starving."