ROWDY bargain-hunters have been warned to behave as stores across Glasgow slash prices for Black Friday.

Police said repeats of last year's chaos will not be tolerated and shoppers could even face jail if they step out of line.

Extra police will be on duty as stores across the country will start sales at midnight on Friday, boasting discounts on a range of goods.

In Glasgow, officers from the festive retail crime unit will be on hand if any scuffles break out.

Last year, police were called to a city supermarket when bargain hunting descended into chaos

Panicked staff were forced to close the doors of Tesco Silverburn shortly after midnight as crowds turned out in force.

Officers attended after trouble broke out – including a bin outside the store being set ablaze.

Trouble flared not long after the sale began and arguments broke out over TVs – just five minutes into Black Friday.

Port Glasgow’s Tesco store also reported exceptionally high numbers of bargain hunters.

Superintendent Graeme Murdoch said: "Last year's event saw chaotic scenes across the country with huge crowds grappling for a bargain.

"We have being working closely with retail stores to support them in preparing for any antisocial and criminal behaviour.

"We will also have additional resources in place to deal with any outbreaks of disorder.

"Officers will attend shops if necessary."

In Glasgow city centre, the St Enoch Centre Game branch will open its doors on the stroke of midnight and trade until 3am.

Meanwhile, Glasgow Fort will open from 8am until midnight.

Across the UK, the National Police Chiefs' Council (NPCC) has warned shops to be prepared and have security arrangements in place.

Deputy Chief Constable Sue Fish, from the NPCC, said: "Having to deploy officers to deal with the fallout of highly-marketed but under-staffed sales in shops diverts valuable resources from other areas of policing and is in most cases avoidable through advance planning."

The Black Friday phenomenon has spread from America to the UK in recent years.

In the USA, traditionally big sales occur on the first Friday after the Thanksgiving holiday.

Shoppers across Britain are expected to spend £3.49 billion on bargains over the weekend starting with Black Friday.

Online sales are predicted to be up 16% on last year.

Around 14.7 million shoppers will take part in the sales bonanza, culminating with "Cyber Monday" when most workers will be in possession of their last pay check of the year.

Earlier this month, Asda became the first retailer in the UK to abandon the one-day sales event.

The store, owned by Walmart, said "shopper fatigue" was behind its decision.