Search-engine company Startpage has launched a service allowing users concerned about privacy to carry out web searches and click on linked pages without being identified, tracked or recorded.

Unlike mainstream search engines that gather commercially valuable information about user behaviour, privately held Startpage (www.startpage.com) has focused on privacy since 2005.

Startpage - also known as Ixquick outside the United States and Britain - had already offered private searching, but users would leave the company's protection when they clicked on a search result and entered a third-party website.

The new service offers use of a Startpage proxy that means the user is invisible to all websites, though pages load more slowly since Startpage must first retrieve the contents and then redisplay them.

"My wake-up call came last year," says Katherine Albrecht, who runs US media relations and marketing for Startpage and who says she noticed Google Inc had installed a programme monitoring users who typed in terms indicating they had influenza - and was sharing the information with the US Centre for Disease Control.

"I had been a privacy advocate for 10 years, but even so I was using Google just like everybody else," she said.

The chief executive of Google, which dominates the global web search market, outraged critics last month with comments in a TV interview. "If you have something that you don't want anyone to know, maybe you shouldn't be doing it in the first place," Eric Schmidt said in an interview on news channel CNBC.

"The reality is that search engines, including Google, do retain this information for some time," he said. "We are all subject in the United States to the Patriot Act. It is possible that that information could be made available to the authorities."