The annual stampede to buy presents for all the family will reach its climax this weekend with 20 million people searching the shops for the best bargain.

However, there will be no need for sharp elbows as a record spending spree will be done online in what is being called Mega Monday. Shoppers will spend £5 billion on gifts and food, boosting the total online shopping bill for December to £15 billion.

Britons will begin their Christmas shopping in earnest today and sales are expected to peak on Monday, the day of the week that historically records the highest number of online purchases.

Monday is the traditional big day for online shopping because buyers usually turn to the internet after having failed to find what they wanted in shops at the weekend. They also go online to see if they can find a better deal on an item seen in a shop.

The internet shopping boom is causing concern among high street retailers, which have experienced a gloomy start to the Christmas season. The number of shop visitors fell by nearly 3 per cent last month compared with November 2006, according to the Retail FootFall Index. Research by Hitwise suggests that visits to online shopping sites rose by 22 per cent.

The two main reasons for the online shopping surge are that consumers are increasingly comfortable with negotiating the internet and retailers have devoted more effort to their online stores. Confidence in website security and cut-throat competition have also lured shoppers online.

Research by Deloitte suggests that 44 per cent of people will buy at least one present over the internet. Tarlok Teji, head of retail for Deloitte, said that consumers had not been put off by the horror stories of last year, when 500,000 presents ordered before Christmas arrived too late. “Certainly this year we’ve noticed that retailers are better geared up to make it happen,” he said.

He predicted that high street shops would have a healthy Christmas period, but that the new year would be bleak as consumers react belatedly to the global credit crunch. “Christmas will be the last hurrah. The new year is going to be tough. This feels like 2005, when people carried on despite hard times and cut back after Christmas. I expect February and March is going to be very tough indeed.”

Men are more likely to shop online than women, with 48 per cent saying that they would use the internet for presents. More than half of 16 to 44 year-olds would buy gifts online, compared with 15 per cent of pensioners.

Shoppers expect to spend about ten hours searching for presents on the internet, according to research by Visa, although people are increasingly frustrated by search engines not turning up relevant results. Most people thought that nine out of every ten hours spent looking were useful. The move to online shopping is hurting high street shops, experts said. Of the £26 billion increase in retail sales in the past five years in real terms, nearly £24 billion of that was online growth, according to figures compiled by the Office for National Statistics and the Interactive Media in Retail Group (IMRG). Experts predict that online sales will be worth £46 billion this year — an increase of £16 billion.

James Roper, chief executive of IMRG, said that shops had reacted slowly to the challenge posed by the internet. “Only 46 of the top 1,900 retailers had a transactional website at the beginning of the year. By the end almost all of them will. The biggest retail brands are only just beginning to take this seriously.”

If high street shops are to survive, they must play to their strengths, he said. “They have got to make shopping a pleasurable experience.”

The auction website eBay predicts that it will see 2.7 million bids on Sunday, double the daily average. Its research found that 67 per cent of respondents went online because of its convenience, 51 per cent thought it was cheaper, 38 per cent wished to avoid queues and 21 per cent thought that the internet has a wider range of goods.

The biggest turn-off for internet shoppers was fraud, the Deloitte survey suggested, with 29 per cent of people worried about being ripped off. More than a third of people prefer to handle the products before they buy them, and 29 per cent simply prefer the high street shopping experience.

People in East Anglia (52 per cent) and Scotland (50 per cent) are most likely to shop online while those in the West Midlands (37 per cent), North East, East Midlands and South West are least likely (all 39 per cent).

However, despite the trend for increasing use of the internet, there is still some work for the online retailers to do, according to Deloitte, with 64 per cent of retailers saying that online sales still only account for 10 per cent or less of total sales at Christmas.

The Deloitte survey findings were based on interviews with 1,000 adults.

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