At least three people have been arrested for fighting over Black Friday bargains as huge crowds caused mayhem in shops across the UK.

Many supermarkets put on extra staff to deal with the frenzy starting at midnight but police had to be called to several shoppers worried about the crowds.

Metropolitan Police officers were called to three Tesco stores in London in the early hours of the morning amid fears of confrontations in heated queues.

After attending the 24-hour supermarkets in Edmonton, Willesden and Surrey Quays, a spokesperson said no one had been injured or arrested.

“Officers have worked with store staff to ensure that sale-goers were able to enter and exit the stores safely,” he added.

Tesco branches in Cardiff and Belfast also reportedly saw scraps as customers came to blows after hours of queuing.

South Wales Police said they attended a supermarket twice with concerns over “customer conduct” and footage of chaotic scenes in Belfast showed people trying to wrestle discounted electrical goods off other shoppers.

Police in Manchester appealed for calm after arresting two people at Tesco and a branch in Stretford, Trafford, had to be closed just half an hour after opening after fights broke out and a woman was injured by a falling television.

A tweet said: "At least two people arrested at #BlackFriday sales events already this morning. Keep calm people!"

Elsewhere shoppers described scenes of "carnage" as people scrambled for the best deals.

Black Friday 2014: Shopping frenzy hits the UK Show all 10 1 /10 Black Friday 2014: Shopping frenzy hits the UK Black Friday 2014: Shopping frenzy hits the UK London Shoppers wrestle over a television at an Asda superstore in Wembley REUTERS/Luke MacGregor Black Friday 2014: Shopping frenzy hits the UK black-friday-uk-7.jpg A member of staff intervenes as shoppers wrestle over a television REUTERS/Luke MacGregor Black Friday 2014: Shopping frenzy hits the UK London Shoppers wrestle over a television at an Asda superstore in Wembley Black Friday 2014: Shopping frenzy hits the UK London Britain's high streets, malls and online sites were awash with discounts on Black Friday as more retailers than ever embraced U.S.-style promotions, seeking to kickstart trading in the key Christmas period Black Friday 2014: Shopping frenzy hits the UK London Shoppers force the exit at the Asda store in Wembley Black Friday 2014: Shopping frenzy hits the UK London Shoppers try to grab items at the Asda store in Wembley Black Friday 2014: Shopping frenzy hits the UK London Desperate shoppers compete to purchase retail items at an Asda superstore in Wembley Black Friday 2014: Shopping frenzy hits the UK London Shoppers wait outside to enter the Asda store in Wembley Black Friday 2014: Shopping frenzy hits the UK London Shoppers queue outside a branch of Foot Locker on Oxford Street Black Friday 2014: Shopping frenzy hits the UK London Shoppers queue to purchase retail items on Black Friday at an Asda superstore in Wembley

One person who bagged a coffee machine at a knock-down price tweeted: "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."

Sir Peter Fahy, chief constable of Greater Manchester Police, criticised shops for failing to provide enough security, saying the chaos should have been expected.

“The events of last night were totally predictable and I am disappointed that stores did not have sufficient security staff on duty," he added.

“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.”

Those hoping to avoid the overnight queues by shopping online were also disappointed when the websites of several major retailers went down with the huge surge in demand.

Argos is one of those limiting visitors, while Curry’s has a queue of at least 20 minutes to get on its site.

Tesco Direct, Game and Topshop were also affected as online shoppers flooded the websites shortly after midnight.

British retailers are increasingly capitalising on the American tradition of Black Friday, which is historically the big sales day that follows the Thanksgiving holiday.