The number of Google+ fans for the site's top 100 brands grew at a 1,400% pace last month, but almost all of the new followers were concentrated in the top 10 brands on the social media site, according to a new report.

The top 100 brands on Google+ saw an increase of 3.1 million people in what Google+ calls circles, according to social media analysis firm BrightEdge, but the top 10 brands accounted for more than 3 million of the new followers.

BrightEdge said the results point to a challenge brands outside of the top 10 on Google+ have and it said Google's challenge will be to increase users across the entire site.

"We expect to see continued consumer adoption of Google+, but expect brand adoption to stay relatively constant," BrightEdge said in its report. "Most of the brands that will adopt and focus on Google+ pages appear to have done so, the next challenge for Google is adding followers."

The top brand on Google+ is fashion retailer H&M, which has 462,000 followers, while Samsung (372,000), Pepsi (350,000), Coca-Cola (336,000) and Starbucks (335,000) round out the top five. Google itself dropped eight spots to ninth, according to BrightEdge, with 194,000 followers in its circle.

While the top brands on Google+ saw fast growth in January, those accounts are dwarfed by the number of consumers interacting with the top 100 brands on Facebook, with the latter having 100 times more, BrightEdge said.