Google cleared a major regulatory hurdle on Thursday after the Federal Trade Commission, the US antitrust regulator, approved the Internet search giant's bid to buy online advertising company, DoubleClick Inc.

In a four to one vote, the Federal Trade Commission said the merger is unlikely to substantially lessen competition in the online advertising market.

Although interested parties have raised concerns about the proposed acquisitions impact on consumer privacy, the commission observed that such issues are 'not unique to Google and DoubleClick, and extend to the entire online advertising marketplace, according to an FTC statement.

The search giant first announced the proposed purchase of the online ad provider earlier in April for $3.1 billion in cash. The FTC opened an antitrust review of the deal in May.

Commissioner Pamela Jones Harbour voted against the merger and issued a separate statement to explain her reason. It's because I make alternate predictions about where this market is heading, and the transformative role the combined Google/DoubleClick will play if the proposed acquisition is consummated, she said.

Privacy advocates have strongly opposed the deal because the united company would hold a vast amount of data. Google already stores individual Web surfing habits, including search queries, IP addresses and cookie details for around 18 to 24 months.

The FTC addressed the concern.

The customer and competitor information that DoubleClick collects currently belongs to publishers, not DoubleClick, according to the ruling.

Restrictions in DoubleClick's contracts with its customers, which those customers insisted on, protect that information from disclosure, and we understand that Google has committed to the sanctity of those contracts, they added.

Google CEO Eric Schmidt retaliated reaffirming the company's commitment to protecting users' privacy.

For us, privacy does not begin or end with our purchase of DoubleClick, Schmidt said. We have been protecting our users' privacy since our inception, and will continue to innovate in how we safeguard their information and maintain their trust, he added.