Facebook users spend more time on the social network on their mobile phones,where monetization and revenue is far weaker than on the desktop site.

According to digital analytics firm comScore, Facebook users on mobile phones—those running iOS, Android and BlackBerry OS—spent 441 minutes per month on the social network during the month of March. This compares with 391 minutes of usage via the traditional desktop site.

That's nearly an extra hour each month—time that advertisers are eager to tap into.

comScore's findings demonstrate just how important the mobile market will be to Facebook's continued success. In the company's February IPO filing, founder and CEO Mark Zuckerberg admitted that "if users increasingly access mobile products as a substitute for access through personal computers, and if we are unable to successfully implement monetization strategies for our mobile users, our financial performance and ability to grow revenue would be negatively affected."

Facebook isn't sitting idly by, however. It acquired mobile photo-sharing app Instagram last month for a whopping $1 billion in cash and company stock, a move viewed largely as an attempt to bolster the company's mobile strategy. Instagram passed 50 million users earlier this month, and is said to be adding an additional 5 million users each week.

In an interview with Bloomberg, Richard Nunn, media analyst at Charles Stanley, said that this so-called "dwell time"—how long users spend on Facebook each month—is a "big factor for advertisers, and therefore, revenue." Last year, the company introduced sponsored posts into users' mobile news feeds, but Nunn believes it is only a matter of time before users see full-fledged advertising too.