Jessie J has cancelled tomorrow’s show at Alnwick Pastures, after falling ill with a viral infection.

The popstar was due to perform before a sold-out audience of 12,000 fans in the shadow of Alnwick Castle.

But less an hour ago, she issued an apology via Twitter saying she had been forced to pull tonight’s show at Pontypridd’s Big Weekend in Wales, following the advice of her doctor.

It sparked a wave of speculation on social networking sites whether the north Northumberland gig would go ahead as planned.

But just minutes ago, promoters KAL Music announced that Jessie would not be travelling north.

Their statement reads: “On behalf of concert organisers KAL Music Limited, we regret to announce that due to the unexpected illness of Jessie J, we have been forced to postpone the concert at Alnwick Castle this Saturday, July 21, and reschedule to a later date.

“Following a visit to her doctor this morning, blood tests have revealed that Jessie is suffering from CMV, a virus which has caused her considerable fatigue. Doctors have advised that the exertion of performances this weekend would be likely to prolong the recovery period.

“The concert has now been rescheduled for August 25 with all existing tickets valid for this date. Any refunds will be made at point of purchase. Please contact your ticket provider directly for details.

“All refunded tickets will be re-issued and made available for purchase to the public at a later date.”

A spokesperson from KAL Music Limited said: “On behalf of KAL Music Limited we would like to extend an apology to all concert ticket holders for any inconvenience

caused. We are hugely disappointed to have to postpone Saturday’s performance but are pleased to have already confirmed an alternative date for the concert to go ahead.

“We hope that all ticket-holders will be able to attend what is sure to be an incredible event. We wish Jessie J a speedy recovery. Jessie is extremely upset to be disappointing her fans at such short notice but looks forward to seeing everyone on the 25th.

All tickets remain valid for the new date.”