Mark Ronson says he wouldn't have made 'Rehab' with Amy Winehouse if he thought she was "in a bad way" on drugs at the time.

The studio wizard was speaking to mark the 15th anniversary of the late music legend's seminal 2006 LP 'Back to Black', which reached the milestone this week, and he has insisted he wouldn't have suggested putting out "a funny song about not going to rehab" if the 'Valerie' hitmaker herself was going through a bad phase with substance addiction.

Speaking about the record's lead single to Zane Lowe on Apple Music Hits, Mark recalled: "When we came out with 'Rehab' too, it was because she was just telling me the story about how her family came over and tried to make her go to rehab.

And she was like, 'No, no, no.' And I just saw the way she said it and delivered it, it had a cadence, it sounded like a song.

"So we went back to the studio, but she was really together. She wasn't doing any drugs ... If this was a person who looked like they were in a bad way or whatever, I would definitely not be saying like, 'Hey, let's make a funny song about not going to rehab.'"

Amy died of accidental alcohol poisoning, aged 27, in 2011, and the 46-year-old producer believes that 'Rehab' is not the singer's biggest-selling song because since her passing it's too "painful" for people to listen to.

He explained: "It felt like such a closed chapter in the past that obviously now that's why that song ... I don't know what the numbers are, but I'm curious, that's not one of her biggest songs, even though it's essentially her biggest hit, because now it's a little more painful to listen to that message very specifically. It's too on the nose or direct."

The song peaked at number 7 in the UK Singles Chart and number 9 in the United States on the Billboard Hot 100, while it scooped three Grammy Awards and Ivor Novello.

Listen to the full anniversary special anytime on-demand on Apple Music at apple.co/_EssentialAlbum.