Google has issued proposals to the European competition commissioner over concerns it abused its dominant position in search.
But Google's response was met with stern words by European consumer groups, who called for an outright "end to manipulated search results".
Google has been under investigation by the European Commission and its antitrust head Joaquin Almunia for two years.
The commission is concerned that Google's dominance has negatively affected competition on the web.
In May Almunia listed the four areas of concern, including:
- Google displaying its "vertical" search services, for instance Google News, differently than links to outside websites.
- Copying material from other websites for use in search, ie reviews, news and other content
- Displaying search results on other websites when powering their search box, resulting in "de facto exclusivity"
- Preventing or restricting "portability" of campaigns from its AdWords campaign to competitors
Google CEO Eric Schmidt's letter to the EU was not made public, but Google says it "continues to work cooperatively with the process".
The search giant could face a fine of up to 10% of its revenue if the EC finds against it - which the BBC said could be up to £2.4bn.
Monique Goyens, director general of the European Consumer Organisation (BEUC), made up of dozens of European consumer groups, said in a statement:
"Google is the daily 'go-to' search engine for millions of consumers, so the notion of sought content being unfairly stacked is cause for considerable concern. Consumers are harmed if provided with partial or biased query results, as it cuts out the chance to make informed choices.
"We are encouraging the commission to ensure the offered remedies put an end to manipulated search results. There should not be a dominant cartographer of the internet."
Meanwhile the Brussels-based lobbying group Initiative for a Competitive Online Marketplace, which is largely funded by Google's competitor Microsoft, slammed Google's response and claimed it was a "recognition of illegal anti-competitive behaviour".
ICOMP's counsel, David Wood, said "the future development of the Internet" was at stake, warning of "grave consequences for online competition, innovation and consumer choice".