Shoppers were left baffled when their car key fobs stopped working for more than an hour.

Customers at Asda Gravesend believe the bizarre incident was caused by a radio frequency jammer.

Mark Hill, 57, was even forced to call Britannia Rescue, when it looked like he'd be unable to drive home.

The retiree, who lives in Gravesham, originally reached the store at about 11.30am on Tuesday.

He said: "I drove into Asda as I often would, but when I pressed the key fob to lock my car, it didn't work.

"I thought it must be the battery and changed it, but when I pressed it, it still didn't work."

After locking his car with his key, Mark went into the supermarket for about half an hour, before returning to the vehicle.

"There were alarms going off, and other people who also couldn't get their cars started..." Mark Hill

He said: "The fob still didn't work when I came out, and I saw other people around me on their phones.

"I asked the man beside me if he was also having problems, and he said he couldn't get into his car.

"There were alarms going off, and other people who also couldn't get their cars started."

Despite having a key, the immobiliser in Mark's car was preventing it from moving - prompting him to call Britannia Rescue just before 12.30pm.

Luckily, by 12.45pm, things had returned to normal, and a recovery vehicle wasn't needed - leaving staff and customers to question what had happened.

Mark believes the incident could technically only have been caused by a radio frequency jammer, which prevents devices from receiving radio transmissions.

He said: "In my opinion, it was some sort of criminal activity, or someone who's got a jammer playing around."

While it's not a problem Mark has experienced before, he thinks "it's certainly not a one off", after reading a similar news report from elsewhere in the country.

Kent Police spokesman James Walker said: "Police were notified of suspicious activity in a supermarket carpark in Imperial Retails Park, Gravesend at 12.17pm on Tuesday, April 9.

"It is reported that a number of cars would not lock and there was concern that this may lead to car theft.

"Police have spoken to security staff and will review CCTV."

Read more: All the latest news from Gravesend