The policy change, implemented on Thursday, means private data collected by one Google service can be shared with other platforms, making it easier for Google to combine the data to build up a detailed profile of one person to target advertising at them.
Google claims that combining the data into one profile also makes search results more relevant and allows a user to cross-navigate between different services more easily.
Peter Fleischer, Google’s global privacy counsel, said: “We are committed to providing our users with a seamless experience across Google’s services, and to making our privacy commitments to them easy to understand.”
Google’s search engine has a market share of more than 90 per cent in the EU, with rival services such as Microsoft’s Bing gaining little traction. The Commission is already examining whether Google uses this dominance to stop rivals from entering the market.