Facebook has agreed to acquire Snaptu, an Israeli start-up that makes apps for feature phones, for an estimated $70 million.

Facebook recently worked with the mobile development firm to build an app for lower-end cell phones that will be accessible free of data charges in a handful of overseas markets. The company says its app provides a smartphone-like experience to more than 2,500 devices.

The deal was announced today by Snaptu in a company blog:

We soon decided that working as part of the Facebook team offered the best opportunity to keep accelerating the pace of our product development. And joining Facebook means we can make an even bigger impact on the world.

Facebook confirmed the acquisition but declined to reveal financial details.

"Snaptu is a start-up run by a highly innovative collection of engineers and entrepreneurs, who we already work closely with to offer a Facebook mobile application for feature phones," Facebook said in a statement today. "As part of Facebook, Snaptu's team and technology will enable us to deliver an even better Facebook mobile experience on feature phones more quickly."

The acquisition is expected to close in a few weeks and has been estimated by the Israeli media to be worth about $70 million.

While smartphones command the most attention in the mobile sector, feature phones still dominate sales. Of the 417 million mobile phones sold worldwide in the third quarter of 2010, smartphones accounted for 19.3 percent of sales, or about 81 million units, according to market researcher Gartner.

Snaptu was founded in 2007 with principal backing from Sequoia Capital and Carmel Ventures.

Updated at 10:55 a.m.: with Facebook statement.