Google, which is offering an online bargain service in three US cities, has acquired The Dealmap, a company that aggregates local deals.

"We are impressed with what The Dealmap team has accomplished and excited to welcome them to Google," a Google spokeswoman said in a statement.

"We've been thrilled with the early success of our commerce offerings, and we think they can help us build even better products and services for consumers and merchants," she said.

Financial terms of the transaction were not disclosed.

Google is offering local bargains in New York, Portland and San Francisco in a challenge to online discount star Groupon and the Internet giant plans to expand Google Offers to Austin, Texas, Boston, Denver, Seattle and Washington.

The Dealmap, founded in May 2010, does not offer deals on its own but aggregates various local offers in one place.

It grew to more than two million users during its first year.

"We believe Google provides the ideal platform to help us accelerate our growth and fulfill our mission," The Dealmap said in a blog post.

"We're passionate about helping people save money while having great local experiences, and in Google we've found the perfect partner that shares this passion, as well as our vision and strategy," The Dealmap said.

"We believe that joining Google will help us innovate in new and unexplored areas of commerce," it said.

Google Offers is a rival to Chicago-based Groupon, which offers subscribers online coupons for discounts on a broad range of consumer goods and services.

Groupon, which claims more than 83 million subscribers, rejected a reported $5 billion takeover offer from Google last year and has filed for an initial public offering seeking to raise as much as $750 million.

Facebook has also entered the daily deals space and began offering local bargains to members of the social network in five US cities in April.