Al Green has given Barack Obama his seal of approval after the President belted out a brief rendition of his soul classic Let's Stay Together at a New York City fundraiser.

Obama wowed guests with an impromptu performance at the Apollo Theatre in Harlem and video footage of the event has since gone viral.

After singing the track's opening line, the politician told the crowd his aides had doubted he would burst into song at the gala, saying: "Those guys didn't think I would do it! I told you I was gonna do it!"

Now music veteran Green has spoken of his pride after hearing the president crooning his tune, telling TMZ.com Obama was "terrific".

He adds: "He nailed it. I was thrilled that the President even mentioned my name, and if the President can get the economy going again and get everything going that he wants to, then we'll all be together."