One of Britain's most senior police officers has hit out at stores after "Black Friday" promotions sparked chaos and violence around the country.

Sir Peter Fahy, chief constable of Greater Manchester Police (GMP), criticised shops for failing to provide enough security after fights broke out and huge crowds caused crushes.

Officers were called to a number of supermarkets overnight as thousands of customers sought bargains on what retailers hope will be one of the busiest shopping days of the year.

At least two people were arrested and a woman was hurt after being hit by a falling television, while some outlets were forced to shut to restore order.

Sir Peter said: "The events of last night were totally predictable and I am disappointed that stores did not have sufficient security staff on duty.

"This created situations where we had to deal with crushing, disorder and disputes between customers.

"It does not help that this was in the early hours when police resources are already stretched.

"Across Greater Manchester large supermarkets already make significant demands on policing through calls to shoplifting, anti-social behaviour and thefts of fuel from their petrol stations - much of which is preventable.

"We just ask these stores to work with us to reduce the demands on policing and reduce the risks of disorder and crime."

A number of shops opened at midnight, boasting massive discounts on a range of goods, but shoppers described scenes of "carnage" as people scrambled for the best deals.

GMP said two people were arrested at Black Friday sales events after officers were called to seven Tesco stores across the area. A post on the force's Twitter feed said: "Keep calm, people!"

Shortly before midnight there were reports of several hundred people trying to enter Tesco Central Park in Wigan. Two men were ejected before control was regained.

The Tesco at Ellesmere Shopping Centre in Walkden was closed after a crowd of more than 500 people turned up.

The Tesco Extra in Stretford was closed after fights broke out between shoppers trying to get their hands on sale stock.

A GMP spokesman said: "A woman suffered minor injuries after being hit by a falling television and an ambulance was called. The store was closed at 12.36am, just over half an hour after the sales event started."

A man was arrested on suspicion of assault after he threatened to "smash" a store employee's face in, police said.

Officers were called to Tesco Extra on Barton Road, Middleton, following reports that about 200 people would not leave, despite being told stock had all gone and the doors were locked.

A man was arrested for a public order offence after reports of fighting after around 300 people descended on the Tesco Extra on Stockport Road, Hattersley.

Police were called to four supermarkets in London as people gathered at Tesco stores in Edmonton, Willesden and Surrey Quays and an Asda in Capitol Way, Edgware.

Images posted online showed chaotic scenes in Edmonton, with witnesses describing "mayhem" as discounted coffee machines went on sale.

The area has seen disturbances before, with several people hurt as crowds of thousands forced a nearby Ikea to shut on its opening night in 2005.

Footage from an Asda in Wembley showed people fighting over televisions.

South Wales Police also reported receiving a number of calls from staff at Tesco stores after they became "concerned due to the volume of people who had turned up to sale events".

Officers went to a store on Excelsior Road in Cardiff twice after midnight over concerns about "customer conduct", police said, adding that no arrests were made.

Shoppers described frantic scenes on Twitter. One wrote: "After the absolute carnage that is Black Friday in a Tesco Extra in the North of England, I walked away with a £100 coffee machine for £30."

There were also disturbances in Scotland. Police were called to Tesco at Silverburn in Glasgow which was closed for a period as people clashed over discounted goods. At another Tesco store in Dundee, police were called to similar scenes and a decision was taken by staff to shut the shop.

Sarah Coubrough wrote on Twitter: "Silverburn shut cos shoppers going mental with the sales. Think I'll stick to the online shopping today."

Those seeking cut-price deals online also faced problems, with shoppers struggling to access the websites of Tesco Direct, Currys, Argos and GAME this morning.

A message on the Tesco Direct home page said: "Sorry for making you wait Lots of people are shopping with us at the moment and we need to ask you wait briefly. Don't worry, we'll redirect you to the website as quickly as we can."

Those trying to shop online with Currys were told they would have to wait 25 minutes for access. "We're really sorry that the huge demand for our deals means you're having to wait," the website said this morning. "We really appreciate your patience and we'll have you on our site as soon as possible."

A message on the Argos home page said it was limiting access because of "very high volume" and urged visitors to try again in a few minutes.

ends Page 2: 10:51 A Tesco source insisted they "work closely" with police and take guidance on security measures in stores, adding: "We will work with them following this event to make any improvements for next year."

The supermarket chain had touted the promotion as "its biggest ever Black Friday event", with discounts of up to 70% on 200 electrical, entertainment, DIY and toy products.

Tesco said in a statement: "Over 600 Tesco stores have Black Friday offers available in store.

"In the interest of customer safety a small number of these stores contacted police last night to help control crowds safely and stores are now trading normally."