BlackBerry (BB 0.13%) has seen a surge in downloads of its long-awaited BBM instant-messaging app for Google's Android operating system and Apple's iPhone. The app, which is in its first day of release for the two systems, has been downloaded a total of more than 10 million times, according to a company press release.

This has propelled BBM to the No. 1 position in Apple's App Store list of most popular free programs in over 75 countries, including the U.S. and BlackBerry's native Canada, the company said. At the moment, the app's iPhone version boasts an average rating of four out of a possible five stars from more than 2,850 users.

In spite of its popularity, the app is late in coming to the market. This past May, BlackBerry CEO Thorsten Heins pledged that Android and iOS iterations would be launched during the summer.

This was one of a host of setbacks for the company so far this year. It posted a loss of $965 million in its most recently reported quarter, and speculation is rife that it will soon be sold to an outside investor, either in its entirety or on a piecemeal basis.