Consumers were set to spend record amounts online today as retailers offer a bargain bonanza to make up for lost trade caused by the snow.

While some retailers started sales days ago, the bulk began online from midnight.

An estimated 4.8 million people are expected to spend about £153m on Christmas Day, according to the Interactive Media in Retail Group (IMRG).

Boxing Day spending could top £300m for the first time, it said.

The figures are backed by payments company Visa Europe, which estimates that 960,000 transactions worth £36m will be made on Visa cards alone today. Visa transactions are expected to account for at least £1 in every £4 spent.

IMRG managing director David Smith said: "Christmas Day has become a busy online shopping day in recent years, as people with an eye for value look to take advantage of the 24/7 nature of online retail."

Steve Perry, commercial director at Visa Europe, added: "The lure of early Christmas sales this year will see record numbers of people heading online on Christmas Day to snap up bargains, and we expect online purchases to make up half of all the Visa card transactions we will process on that day."

Comparison website moneysupermarket.com has also predicted this year's Boxing Day sales to be the biggest ever, saying the UK is set to spend £323 million online in a single day.

It has put the increase down to the looming VAT increase coupled with seasonal sales, with the forecast freezing temperatures and planned tube strikes also likely to see shoppers swap the high street for online.

The fact that Boxing Day falls on a Sunday means trading hours are restricted to six hours. However some retailers are opening early to allow customers to browse before they buy.