Emma Watson spoke publicly about Harry Potter co-star Daniel Radcliffe’s reported alcohol addiction on the Late Show last night.

The stunning Watson, who plays Hermoine in Harry Potter is normally articulate in her interviews, but she came up against a curly one when David Letterman broached the subject of Radcliffe’s drinking.

In a recent interview with GQ magazine, Radcliffe, who plays in the blockbuster movie series, said: "I became so reliant on alcohol to enjoy stuff. There were a few years there when I was just so enamoured with the idea of living some sort of famous person's lifestyle that really isn't suited to me." He gave up alcohol last year and cut down on his party lifestyle.

Watson had stopped in to the Late Show for a quick interview before the New York premiere of Harry Potter when Letterman was keen to know if she was aware of her co-star’s problem.

She said, “To be honest, it’s really not something that I genuinely know much about and you should, I mean, he is the one to talk about it.”

The host continued: “Do you drink at all? Do you use controlled substances?”

The 21-year-old Potter actress looked extremely uncomfortable before laughing off the question and saying: “I’m dying here! Can we move on? I don’t want to talk about this!”

Watson later stole the show at the premiere in an eye-catching, strapless, bronze Bottega Veneta gown.