Google, MSN and Yahoo won’t like this.

In a move that seems destined to invite tension with major American search engines, a European Commission advisory body has suggested that those companies delete data collected about their users after six months–a far cry from what most companies currently do.

The recommendation arrived in a 29-page “opinion” published by a European Commission body known as the Article 29 Working Party. Backed by privacy groups, it has been pressuring Internet companies on the search data front for months. The report focused on advertising-supported search engines, as opposed to search functions embedded in Web sites.

The Working Party’s suggestions don’t officially have the force of law yet, but they are expected to be adopted by the EC. The EC already adopted a broader set of data protection laws a decade ago, but this report was meant to address specifically how search engines, including those headquartered outside its borders, fit into that setup.

Privacy in search engines is critical because “an individual’s search history contains a footprint of that person’s interests, relations, and intentions,” which can then be mined by businesses and national security operatives alike.