The watchdog's review says that in general, price comparison Web sites have represented a major step forward for consumers, enabling them to secure better value when buying goods and services, but that some people are missing out on potential savings because of a lack of trust.

The review also says that the role of such sites is likely to become even more important in the future as online sales continue to grow and initiatives such as the Government's 'midata' project put more information in consumers' hands.

As part of its review, the OFT conducted a Web-sweep of 55 price comparison sites which found that a number of sites could improve their privacy policies and their complaints and redress processes. It also identified scope for some sites to provide greater clarity about the way search results are presented, and clear identification of the business operating the Web site.

The OFT's 2007 market study into Internet shopping estimated that if consumers used price comparison Web sites as effectively as they could they would stand to gain additional savings of £150m - £240m per year.

Clive Maxwell, OFT chief executive, comments: "As companies release more data back to consumers under the Government's 'midata' initiative, there will be new opportunities for people to get better value using price comparison sites, so it's important that issues around consumer trust are tackled now."

The midata project is designed to give Brits more access to, and control over, the data that companies hold on them so that they can get greater insight into their own spending habits and improve buying decisions. The plans are likely to give a boost to the development of PFM tools by banks and provide opportunities for account aggregation vendors to make inroads with consumers.