Biba argues that many price comparison sites are effectively giving financial advice when they tell consumers which are the cheapest car, home and other types of insurance policies.

There is a risk, Biba says, that insufficient emphasis is placed on policy features, which means consumers may buy the wrong policy simply because it is the cheapest. There are also concerns that some price comparison tools base their prices on a number of assumption about the applicant, and that this can lead to customers being quoted a price that is not what they end up paying.

Eric Galbraith, chief executive of Biba, said: 'There are still too many people logging on and making a decision solely based on the price of a policy, rather than the protections it offers them and potentially buying an inappropriate policy.

'The current FSA rules were written prior to the growth in aggregator sites. I believe the regulator should now look again at developing more appropriate regulations, to ensure that consumers are being afforded suitable protections.'

The FSA previously looked at the issue of price comparison sites in 2005. At the time it decided that no change in the rules was necessary. However, it confirmed that it would reassess the arguments for further regulation in light of the Biba claims.

Debra Williams, managing director of price comparison service Confused.com, said: 'We support Biba's views that FSA rules are not appropriate, because they were finalised prior to the development of price comparison websites. The research into price comparison websites commissioned by Biba, found that 93% of consumers expect insurance comparison websites to be regulated in the same way as insurance intermediaries – a view which has long been championed by Confused.com, to the extent that we have voluntarily invited the FSA to regulate our activities.'