Sales of 'free laptop' deals that bundle a mobile broadband dongle with a laptop have surged in the run up to Christmas, says Broadband Expert.

According to the comparison website, the number of deals purchased rose by 115 percent in the first week of December compared to the previous month.

Rob Webber, Broadband Expert's commercial director, said: "One reason for the boost in free laptop sales is that these deals are enticing many Christmas shoppers who were initially looking to purchase a standalone laptop. Free laptop bundles are popular because they allow customers to avoid the upfront cost of a new computer."

However, Webber warned consumers to be wary as the total cost of the tariff over the term of the contract can sometimes work out up to 20 percent higher than purchasing the laptop on its own.

"The term 'free laptop' should not be taken at face value," he said. "Providers make sure the price of the hardware is recovered by tying consumers into longer contracts in order to make the money back."

Broadband Expert also said that it saw a similar trend of increased free laptop sales last year but this year's figures suggest sales will easily surpass the number sold last Christmas.

New: Try out PC Advisor's virtual BlackBerry

Laptop buying advice

See all netbook reviews

See also: 65% of mobile broadband users on less than 1Mbps