X Factor winner 2012, James Arthur, has hit out at some of the "mediocre" acts playing at this year's Glastonbury Festival.

The 26-year-old singer also took to Twitter to vent his anger over not being invited to play at the music festival.

He wrote: "Its [sic] sad that I'll probably never play Glastonbury because of the format I was discovered.. Has anyone from xfactor ever played it?"

He added: "Especially sad when you see how mediocre some of these acts are live!! #verybitter."

Arthur recently parted company with Simon Cowell's record label Syco.