Facebook is the most prominent mobile app in terms of reach across the markets surveyed in Arbitron Mobile’s Mobile Trends app panel, with 2 out of 3 smartphone owners using the app monthly.

According to Hannu Verkasalo, SVP of the company, “the growth of Facebook cannot only be explained by organic growth, but the various partnerships and deals Facebook has with carriers and device manufacturers guarantees them with top position in today’s smartphones, specifically in Android and iPhone devices.”

While this app has more than 60 percent reach in the USA, France and the UK, its penetration in Germany is lower, at around 46 percent. Here, Verkasalo said “the fact that other brands, such as Nokia and RIM, are still very strong, explains that the Facebook app does not yet have equal reach compared to other countries.”

The company’s survey also showed that a number of other apps score highly across the four markets, such as Google Search, YouTube and eBay. However, there are also a number of locally-focused apps in high positions, such as the BBC in the UK, Rejseplanen in Germany, and Pages Jaunes in France.

Arbitron said a “representative selection” of smartphone users are invited to install a metering app to their smartphones, in order to enable it to generate data for its Mobile Trends panels. It said its research, which is based on anonymised statistics, are intended to help “not only the traditional mobile operators, such as carriers and device manufacturers but also app developers, advertisers, media agencies and companies.”