Angry Birds maker Rovio is teaming up with a major U.S. retail chain to put its branded toys, books and T-shirts in dedicated areas of thousands of stores nationwide, the Finnish company's marketing chief told Reuters on Tuesday.

The maker of the world's most-downloaded game plans the launch to coincide with the debut later this week of Angry Birds Space, the latest in the series of puzzle games currently being played for a total of 300 million minutes per day.

Angry Birds has been downloaded more than 700 million times on Apple iPhones, other smartphones, iPads and desktop computers. It is also the fastest-growing game on Facebook, but sees itself as an entertainment brand, not just a games company.

We want to make Angry Birds a permanent part of pop culture, Peter Vesterbacka said in an interview in London, comparing the brand to Sanrio's Hello Kitty or Nintendo's Mario. We're just getting started.

Rovio did not want to name the U.S. retailer ahead of the official launch, but it will be bigger than an existing partnership with bookseller Barnes & Noble, where visitors to the stores can pick up game credits for free.

Rovio also plans to open branded retail stores in China soon.

Since the launch just over two years ago of the first Angry Birds game, in which players use a slingshot to catapult birds and destroy green pigs hidden in fortresses, Rovio has grown from a small Finnish startup to a brand worth as much as $9 billion.

It has had to move out of central Helsinki to new headquarters next to mobile phone maker Nokia, and its staff numbers have ballooned to 300 from 50 a year ago.

Asked about the $9 billion valuation, which some media have reported, Vesterbacka said: It's as good a guess as any. He compared Rovio to Facebook games maker Zynga, which went public in December and has a market value of $9.6 billion.

Vesterbacka reiterated that Rovio was in no hurry for a public listing. Its last funding round was last year, when it raised $42 million from venture capital firms Accel, Atomico and Felicis Ventures.

He said Rovio had not needed the money and had raised the capital primarily to attract onto its board investors such as Atomico's founder Niklas Zennstrom, a co-founder of Skype.

This year we'll be very busy, like we were last year, with building up the infrastructure, said Vesterbacka. We can fund our own growth.

(Editing by David Holmes)