BlackBerry maker Research In Motion is stepping up its efforts to take a share of the computer tablet market with the announcement of two additional PlayBook tablets for faster, advanced wireless networks.

RIM said Monday at an industry conference in Spain that it will launch two additional tablets later this year to support fourth-generation networks that are suited to video streaming and high amounts of data.

"We are now building on the BlackBerry PlayBook's many advantages with support for additional 4G networks that will allow enhanced business opportunities for carriers and developers and unparalleled mobile experiences for users," said Mike Lazaridis, president and co-CEO said in a news release.

RIM (TSX:RIM) is expected to have its first PlayBook computer tablet out this spring, likely in March, and will be competing with Apple's iPad and tablets powered by Google's Android operating system.

Apple's iPad isn't yet available for fourth-generation networks.

The Waterloo, Ont., company has announced a family of PlayBook tablets to run on a variety of fourth-generation networks such as Long-Term Evolution and WiMax. The tablets will also work on short-range Wi-Fi networks and can support Bluetooth tethering.

National Bank Financial analyst Kris Thompson said he expects a "pent up" demand for the PlayBook from enterprise users since many businesses don't support Apple or Android's operating systems yet.

"Our view is that the PlayBook is more appealing to enterprise customers than to consumers, at least in the early days," Thompson wrote in a recent note.

Thompson said he's expecting RIM to ship 3.6 million PlayBooks in fiscal 2012 with an average selling price of $481 and 6.2 million units in fiscal 2013 with an average selling price of $450.

RIM is exhibiting at the Mobile World Congress in Barcelona, Spain, a major show featuring the latest developments in mobile communications.

Shares in Research In Motion were down 15 cents in late morning trading at $65.73 Monday on the Toronto Stock Exchange.