Heavy metal rockers Saxon were forced to pull out of a festival performance in Portugal over the weekend (10-11Aug13) after frontman Biff Byford suffered a mystery injury.

The group was scheduled to take to the stage at the Vagos Open Air festival on Saturday (10Aug13), but had to cancel their appearance after doctors advised Byford, 62, against performing.

A statement posted on the band's website reads, "At present the severity of Biff's injuries are unknown and doctors have advised him strongly not to perform. Saxon are extremely sad at disappointing fans in Portugal, and hope they can come back soon."

No further details about Byford's condition have been made available.