Price comparison websites have been issued with a warning after some failed to meet the required regulatory standards.
The Financial Conduct Authority found that the websites operating in the general insurance sector did not always ensure that consumers were given the appropriate information to help them make informed decisions.
The thematic review, published today, said this was particularly important.
The FCA expressed concerns that consumers' focus on headline price and brand when using such comparison tools could distract from crucial product features such as policy coverage and terms.
Some sites failed to disclose potential conflicts of interest.
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Clive Adamson, FCA director of supervision, said by failing to provide clear information, the websites have been "increasing the risk that consumers may buy products without understanding key features such as level of cover or excess levels and purely focus on the price".
FCA officials said while a few websites did provide this information clearly, the level of clarity varied significantly depending on the provider.
Mr Adamson said: "We expect price comparison websites to take on board the findings of the review. It is also important for consumers to understand that not all products are the same and the cheapest product may not always be the best for their needs."
He said: "Price comparison websites have increased in popularity among consumers with an estimated one third of consumers buying their motor insurance policy through them.
"They provide an important service for millions of consumers bringing convenience and simplicity to buying financial products online.
"However, our review found that they were not meeting our requirements in delivering fair and consistent outcomes for consumers. We also found, through our consumer research, that consumers had a number of misconceptions about the services they provided."

The FCA said its other key findings were:
- Price comparison websites did not make clear their role in the distribution of the product or the nature of service they provided. For example, some consumers mistakenly believed that the price comparison website had provided them with quotes on the best policy for their individual needs and had assessed the suitability of the policy for them.
- Not all comparison sites, that were part of a larger group of an insurer or broker, disclosed this potential conflict of interest, which is against FCA rules. However, the FCA found no evidence that these firms used this relationship to their commercial advantage.
- While some price comparison websites had taken steps to comply with their regulatory obligations they had failed to fully implement Guidance published in 2011.