NEW YORK, April 24 - Facebook has bought the fitness app Moves, which helps users monitor daily physical activity and their calorie counts on a smartphone.

The two-year-old Finnish startup ProtoGeo, which developed the app, said Thursday it had been acquired by the US social networking giant, and that key members of its team would be moving to the Facebook headquarters in Menlo Park, California.

Both companies said Moves would continue as a standalone application, rather than be integrated into the Facebook framework.

Moves assured users that "there are no plans to change that or commingle data with Facebook."

"The Moves team has built an incredible tool for the millions of people who want to better understand their daily fitness activity, and we're looking forward to the app continuing to gain momentum," Facebook said in a statement.

Facebook executives told analysts in a conference call Wednesday that they were focused on building up their "ecosystem" of apps as a way to bring more users to the company and, eventually, find more avenues for revenue via advertising or other means.

The company made two large acquisitions earlier this year, spending $19 billion for the instant messaging service WhatsApp and $2 billion for a virtual reality company, Oculus.

No financial details of the Moves deal were given.