PARIS, Nov 23 (Reuters) - Targeted online advertising is set to face increased scrutiny from European Union regulators concerned about invasion of privacy, threatening the growth of a potentially big online revenue-booster for media companies.

"This is a very hot topic that can be expected to be part of our work programme next year," Gabriele Loewnau, a senior legal adviser for the German Federal Commissioner for Data Protection, said on Friday.

The German commissioner currently heads the European Union's advisory body on data protection matters, the so-called Article 29 Working Party.

Recommendations from the working party have been used by the European Commission to get Google (GOOG.O: Quote, Profile, Research) to curtail the amount of time it stored past Web searches to 18 months.