Heavy metal pioneers Black Sabbath have postponed two shows on what they say will be their final tour after frontman Ozzy Osbourne fell ill.

Black Sabbath scrapped plans to play Saturday in Edmonton, Alberta and announced that the band would also push back another Canadian show scheduled for Monday in Calgary.

The band said in a statement that it was postponing the shows as Osbourne suffers "extreme sinusitis" and that the concerts would be rescheduled, with dates to be announced later.

Black Sabbath on January 20 opened a tour in Omaha, Nebraska that will crisscross the world before ending back in the United States on September 21 in Phoenix, Arizona.

The British band, whose influential first album came out in 1970, has vowed that the concerts will be the last and called the tour "The End."

Osbourne, 67, is one of the quintessential figures in heavy metal, known for his fascination with the occult and on-stage theatrics. He has gone on to have a successful solo career.

Previous efforts for a final tour were clouded by concerns over the health of guitarist Tony Iommi, who has suffered lymphoma.

Iommi was one of the creators of the heavy metal sound, taking the blues as the musical base but tuning his guitar down to a dark minor key with intense distortion.