The issue surrounds Google's policy of anonymizing its server logs after 18 to 24 months. According to a Commission source, the advisory group is concerned with how the information is managed, rather than the length of time it is stored.
Google, which confirmed it received a letter from the chairman of the advisory group, said it will respond, as requested, before the group holds its next meeting in mid-June.
Google previously kept consumers' data as long as it was needed. The company now plans to keep server log data, but will enhance the ability to make it anonymous after 18 to 24 months.
"We believe it's an important part of our commitment to respect user privacy while balancing a number of important factors, such as maintaining security and preventing fraud and abuse," Peter Fleischer, Google's global privacy attorney, said in a statement.
"We are committed to engaging in a constructive dialogue with privacy stakeholders, including the (European Commission privacy advisory group), on how to improve privacy practices for the benefit of Google users and for everyone on the Internet," he added.
Google will have until mid-June to respond to the advisory committee's concerns. The committee is expected to review Google's response and may issue a formal recommendation before the summer holidays, the Commission source said.