British pop star Jessie J has scrapped a gig in Wales after contracting a viral infection.

The Domino hitmaker was set to take to the stage at the Ponty's Big Weekend event in Pontypridd on Friday night (20Jul12) but has fallen ill.

I hope you can all understand that I wish I could be there

The star took to Twitter.com to apologise to fans, and admitted the bug has left her too tired to perform.

In a series of posts, she writes, "I want to personally apologise to all my fans who would be going to my show tonight (Pontys Big.W). I have been diagnosed with a viral infection recently that has caused me to be extremely fatigued. "I was hoping to be better but I have been to see my doctor this morning after not feeling great who has advised me I am still in need of rest and to perform will make me worse.

I hope you can all understand that I wish I could be there.

But I'm just not well enough.

Back to bed I go.

So sorry".