One Direction's Niall Horan has appealed to fans to stop throwing things at them while they are performing after being injured during their gig in Amsterdam. 

The 20-year-old Mullingar native injured his knee during a gig for their Where We Are Tour in Amsterdam, Holland last night (June 25) after an over-zealous fan threw something heavy up on stage.

Horan has since asked fans, via Twitter, to be careful with things they throw up during gigs.

He wrote: ''Amsterdam thank you for a great couple of shows! Appreciate you coming.

''Also guys! Can you limit what gets thrown on stage please! Coz somethin thrown at me tonight! Hit my knee! A lot of pain from it!

''Never wana sound like I'm complaining! But only having my operation 5 months ago, I still get a bit of pain and I'm very scared about it. (sic)''

And it wasn't only Niall who was injured. Harry Styles was hit in the face by an unidentified flying object.