RETAILERS are readying themselves for another record Black Friday despite suggestions of shopper "fatigue" after days of discounting ahead of the main event.

The pre-Christmas sales bonanza - previously a 24-hour affair that has become the UK's biggest shopping day - has seen most major retailers start their Black Friday deals almost two weeks early with deals on everything from electric toothbrushes to holidays abroad.

They are promising new deals on Friday and many are extending their opening hours, including Tesco opening the "majority" of its Extra stores early at 5am and John Lewis closing some of its stores later than usual.

Experts have pointed to the evolving nature of the event, which has progressed from brawls over cut-price televisions to last year's "muted" high street turnout, with many predicting increased spending online this year.

Retailers will be hoping for an improved performance from their websites, many of which struggled to cope with the volume of traffic last year.

John Lewis, whose Black Friday offers last year translated into its biggest week for sales in its 150-year history, said it had prepared for a smooth online experience for shoppers and an "atmosphere of calm" in stores.

John Lewis operations director Dino Rocos said: "Additional staff will be on hand across our 48 shops to ensure the high levels of service our customers expect is maintained."

British shoppers are expected to spend £2.3m a minute this Black Friday - a 19 per cent increase on last year - despite warnings that they should "ignore the hype" and exercise caution.

Some 14 million British consumers are expected to participate in the global shopping event, now the biggest shopping day in the UK, and will spend a predicted total of £1.96bn, according to VoucherCodes.co.uk and the Centre for Retail Research.

Online spending on Black Friday is expected to reach £1bn, up 16 per cent on last year, while it is anticipated that the majority who opt for the High Street will spend a lower total of around £961m.

Well over half of online sales, 59 per cent, are set to be made via a mobile device, accounting for £591m of total spending.

A survey for BHS.com found 21 per cent of shoppers planned to spend more this year than last year, and just nine per cent intended to spend less.

Kevin Jenkins, UK and Ireland managing director at Visa, said: "Looking at the spending patterns last year, Black Friday shifted online in a big way.

"Spending was predominantly spread across the four days between Black Friday and Cyber Monday.

"With major retailers focusing more on online and mobile channels this year, as well as launching promotions from as early as last week, the shape of Black Friday spend is likely to evolve from last year."

Consumer group Which? has already warned shoppers to "do your research" after finding that half of last year's deals were cheaper in the months before and after Black Friday.

John Willcock, head of credit cards at Post Office Money, said: "Many people feel that retailers are extending the Christmas sales season to be longer than ever before, in an effort to get people in-store and shopping online, leading some to feel a certain element of 'discount fatigue'.

"However, our research shows that shopping events such as Black Friday and Cyber Monday are still very popular as people try to offset Christmas expenses."

Amazon and Asda behind Black Friday's introduction to UK

ONLINE giant Amazon and Walmart-owned Asda both take credit for introducing Black Friday to the UK.

Asda is not taking part again this year, reasoning that its customers prefer year-round deals rather than a single day of sales, although its decision to withdraw came after some stores were the scene of brawls as customers fought over cut-price items.

Apple has previously opted out of the event but is teasing visitors to its website with the promise of deals on Friday, but Next and Ikea have ruled themselves out.

Amazon has been offering Black Friday deals since last Monday, and new offers as of today include its bestselling Fire tablet available at a "lowest-ever" price of £29.99.

Customers can also save up to 45 per cent off selected Le Creuset lines, and its Paperwhite kindle is on sale for £79.99, a £30 saving.

Amazon is also launching thousands of 'lightning deals' on limited quantities of products for a short time.

John Lewis is already offering a £375 saving on the Samsung UE65KU6500 ultra HD smart tv and £175 off the Dyson DC75 Cinetic Big Ball Upright Vacuum Cleaner,

Argos is running a 13-day sale with discounts on items such as Dyson vacuum cleaners and tvs, while Boots launched its deals on Saturday with more than 50 per cent off some electric toothbrushes and Braun shavers as well as savings on electricals, beauty and fragrance.

Debenhams is offering up to half price on certain items every day this week, including beauty, health and electrical items, furniture and 40 per cent off toys.

House of Fraser has launched its six-day Black Friday event with 50 per cent off brands including Barbour, Ugg and Michael Kors, among other deals.

Supermarket giant Tesco has an 11-day sales event running which will continue until December 1. The main event on Black Friday itself will see the majority of Tesco Extra stores opening at 5am.

Online auction site eBay is revealing new offers each day until November 29.