Rovio, the Finnish developer behind the Angry Birds smartphone game, raised $42 million from investors and named Skype co-founder Niklas Zennstroem to its board.

The funding round was co-led by Accel Partners, which has previously backed Facebook, Admob and Baidu, and Zennstroem's venture capital firm Atomico Ventures, Rovio said on Thursday. Angel investor Felicis Ventures also participated.

Rovio wants to expand across markets including mobile, social media and other platforms, and via merchandising and media production and partnerships, it said.

Angry Birds will continue to grow and we aim to create more similar success stories, Mikael Hed, chief executive and co-founder, said.

Hed told Reuters in August he planned to turn Angry Birds into a fully fledged entertainment brand in the way Walt Disney's Pixar has done with characters from Toy Story and Monsters, Inc.

Angry Birds -- in which players have to help birds destroy the pigs who stole their eggs, with the help of a slingshot -- has broken new ground in mobile gaming by staying at the top of the charts, unlike most mobile-game crazes.

It is being played by 40 million monthly active users, Rovio said.

This investment will give Rovio wings, Zennstroem said. Angry Birds is one of the fastest-growing online products I've seen, growing even faster than Skype, and the company has done a brilliant job of extending it across different platforms and merchandise.

Over 75 million paid and ad-supported versions have been downloaded. Revenue share and revenue per copy vary, the company said.

Rovio said in August it is aiming for 100 million Angry Birds downloads through the next year or two.

Rovio was founded in 2003 after three students including Niklas Hed -- Mikael's cousin and now Rovio's COO -- won a game-development competition sponsored by Nokia Oyj and Hewlett-Packard CO. It changed its name from Relude in 2005.

(Reporting by Nicola Leske; Editing by David Holmes)