Google's $3.1 billion purchase of DoubleClick has drawn more heat from privacy critics. This time BEUC, a major European consumer group, said it feared the acquisition would threaten European Union privacy rights.

"They have so far complementary databases with private data," Cornelia Kutterer, BEUC's legal adviser told The New York Times. "If they merge them, this could lead to unmatched databases of profiles. If they can combine them, this could lead to a violation of user privacy rights.''

The BEUC's complaint is the latest in a series of criticisms leveled at Google by privacy advocates in Europe and the U.S.

While the Federal Trade Commission continues to review Google's DoubleClick purchase, EU regulators also have considered the legal ramifications of the deal. In June, Google soothed concerns of some EU regulators by announcing that it would refrain from storing personal data for longer than 18 months. The previous policy had been to store data for up to two years.