Some insurance comparison websites contain out-of-date information and can mislead customers, according to an investigation by the Financial Services Authority (FSA).

As part of its research, the body found cases where compulsory excess levels were either incorrect or not included in the quote, incorrect pricing and sites only offering a limited number of product features.

But the FSA also found that others were "clear, fair and not misleading". The organisation now intends to visit each of the 17 price comparison websites it studied to verify the accuracy of the information they provide.

"We are keen that the market develops in a way that ensures customers are treated fairly, and expect comparison sites to provide information that is clear, fair and not misleading," said Ed Harley, head of financial promotions at the FSA.

In 2007 price comparison sites accounted for 25% of all motor insurance policy sales.