Niall Horan has slammed a fan for taking a picture of him while he was asleep on a plane.

The One Direction singer was flying from London to Chicago to see his friend Ellie Goulding perform at the Lollapalooza music festival, when he met the fan, who snapped a picture of him sleeping after he declined a selfie.

The fan shared the picture on social media and wrote: ''And to sum up the perfect European adventure, I sat directly next to Niall from One Direction for 9 hours on my flight home from London last night. He was sick and asked for no selfies, but here is a pic I snapped when he was sleeping lol he was so friendly.

''Talked about Ireland, LSE, lolla and more. Not a British Duke...But an Irish popstar will do. Thanks for treating me so well Europe! (sic).''

Niall, 22, was furious when he found out about the picture and shared the post on Twitter with the words, ''I think this s**t is unreal. I mean if you can't sleep on a plane without people taking photos of you,what can u do (sic).''

Meanwhile, Simon Cowell recently hinted that Niall is set to announce a solo deal with Sony soon.

Simon - who guided Niall and his One Direction bandmates to fame after discovering them on the UK version of 'X Factor' - showered praise on the singer and revealed that a big announcement is coming.

He said: ''I think they're all gonna do great. Niall is the most loyal. We are expecting to announce something soon with him. I've always known he's loyal.''

Singer John Newman also revealed that he has been working on new material with Niall.

He said: ''I was having a text back and forth with Niall Horan the other night about some ideas, which is cool.''