England defender Ashley Cole accidentally shot and wounded a 21-year-old student on work experience at his club's Cobham training ground, it was revealed last night.

The Chelsea left-back was reported to have been "larking about" with a .22 calibre air rifle when he fired at student Tom Cowan from just five feet away.

Sources at Chelsea Football Club told the News of the World how Cowan was treated by medics at the ground and allowed to rest following the incident. But two days later the wound was still weeping and he was tended to again by medical staff.

"It's truly inconceivable that a Premier League footballer could bring a gun to the training ground," a source said. "But Ashley pulled the rifle from a box and started larking about with it in the changing room."

Former Arsenal star Cole, 30, arrived at Chelsea's Cobham training ground in Surrey holding the weapon, complete with a muzzle and nightscope, last week. The incident was witnessed by a dozen members of staff, but Cole claimed he was unaware that the rifle was loaded. Cowan, a Loughborough University sports science student, was at the team's training ground as part of a year's work placement with Chelsea.

On Wednesday, he was called into a three-hour meeting with "deeply worried" Chelsea officials to discuss the accident, and a day later his father, Ronald, a 51-year-old quantity surveyor, held a second meeting at the club where he demanded to know what action would be taken against Cole.

A .22 air rifle is the most powerful type of weapon that can be legally owned in Britain without a licence. Under British law the incident could be deemed actual bodily harm which carries a maximum penalty of five years' imprisonment and an unlimited fine.

Cole, who earns £110,000 a week, is reported to have been given a severe dressing down, and has formally apologised to Cowan.

It is not the first time that Chelsea's Surrey training facility has been at the centre of controversy. In December 2009, the club's captain, John Terry, was caught asking for a £10,000 cash payment to secure behind-the-scenes tours for various individuals without the permission of the manager.

Terry later claimed that the proceeds of the tours had been given to charity.

• The following correction was printed in the Observer's For the record column, Sunday 6 March 2011. We said the weapon was "complete with muzzle and nightscope". All rifles have a muzzle – it's where the projectile exits.