AN Alexandria man has confessed to setting fire to a shop while staff and shoppers were inside.

Nathan Sartain pleaded guilty to starting the blaze at the Scotmid in Tullichewan Drive, Alexandria, on October 16 last year.

The 30-year-old's crime caused extensive damage.

He admitted the charge at a hearing at Dumbarton Sheriff Court on October 29.

Fiscal depute Dana Barclay told the court that CCTV showed Sartain at the rear of the store.

Sartain, of McPherson Lane, Alexandria, was crouching nearby to what became the seat of a fire.

"He appears to be doing something with his hands with his back to the camera, then making off," said Ms Barclay.

"On CCTV within seconds of leaving, a fire has started where he was kneeling. It thereafter spread to the roof and interior of the building."

Around 9.15pm, a member of the public contacted Scottish Fire and Rescue Service, who arrived within five minutes.

The watch commander said a bin was on fire and it spread via the ventilation system to the interior.

Sartain was traced the next day and was arrested. There was no detail for the court about the extent of the damage of the fire, nor how many people were inside at the time.

Defence solicitor Kenny McGowan said his client had spent a period in hospital care in the past year and was supported in court by his parents.

Sheriff Frances McCartney deferred sentence until November 26 for reports to be prepared.