The search giant has come in for its share of criticism regarding privacy, specifically over what user search information it retains and how it manages user information across its growing stable of web services and social networking sites.

The most vigorous and public criticism has come from Europe. The European Commission demanded that the company reduce the length of time it holds Europeans’ search details, in order to comply with data protection laws here.

This approach generated a debate with Google over what constitutes personal information in the context of an internet search. Google now makes search details on its systems anonymous after 18-24 months.

The Article 29 group, comprising all the EU data protection commissioners, continues to argue for shorter retention periods, and also objects to the retention of IP addresses, which can identify an individual computer user.

Google has said it is required to keep information under EU data retention laws; the group says Google is not subject to those laws, as they are intended for ISPs and telecommunications companies.

London-based privacy watchdog Privacy International criticised the company last year, ranking it “hostile” and “worst” on privacy out of a number of web firms because of the vast amount of information it generates, and what PI said were poor privacy policies and inadequate responses to complaints.

Google argued that the criticisms were unfair and showed a misunderstanding of its policies.