"This is a very hot topic that can be expected to be part of our work program next year," Gabriele Loewnau, a senior legal adviser for the German Federal Commissioner for Data Protection, told Reuters.
The German commissioner heads the EU's advisory body on data-protection matters and is known as the Article 29 Working Party. The party, which currently is investigating online privacy, previously had Google curtail its data retention of Web searches in Europe to 18 months.
The announcement came after more than 13,000 Facebook users signed a petition protesting the social-networking site's new advertising system, which alerts members of friends' online purchases. The petition drive was led by U.S. civic-action group MoveOn.org.
Facebook members can opt for their online transactions to remain private, but critics argue the option is easily overlooked on the site.
Targeted advertising differs from traditional online advertising in that it's designed to correspond with the user's habits in browsing and online purchases, not the content of a website.
Online advertising is the fastest-growing segment of the ad industry, gaining more than 25 percent a year, Reuters reported.