Social network Facebook has overtaken Google in visits for the first time, at least in the US, says Hitwise.

According to the web metrics firm, Facebook accounted for 7.07 percent of all US web visits to Google's 7.04 percent in the week ending March 13.

Hitwise also revealed that Facebook had 400 million users in February this year, compared to 20 million in April 2009.

"The market share of visits to Facebook increased by 185 percent last week compared with the same week in 2009, while visits to Google increased by nine percent during the same time frame," said Heather Dougherty, research director at Hitwise, in a blog.

Dougherty also said Facebook was the most visited website in the US on Christmas Eve, Christmas Day, and New Year's Day as well as the weekend of March 6th and 7th.

See also: How to use Facebook safely