Nintendo has shipped more than 50 million units of its Wii game console since its launch three years ago, becoming the fastest-selling console ever, the company's president said on Wednesday.

The Wii, launched in 2006 into pitched competition with Microsoft Corp's Xbox and the Sony PlayStation, has proven popular with consumers and is credited with helping expand the gaming market to more casual users.

Frankly speaking, before the launches of the Nintendo DS and Wii systems, almost no one expected them to reach the current level of mainstream acceptance, President Satoru Iwata told the Game Developers Conference in San Francisco. It's even beyond what we possibly hoped for.

The market has expanded as video games have been accepted by more consumers than ever before.

Speaking at the same venue where in 2005 he talked about a new product code-named Revolution -- which turned out to be the Wii -- Iwata said the console is now the fast-selling in history.

The Wii has far outsold rival consoles Xbox 360 and Sony's PlayStation 3.

Stressing its appeal to a more casual audience, Iwata said around 20 percent of Wii households in the United States, or 3 million people, had no other video game system in their home when they bought the console.

This month, Nintendo announced that total shipments of its DS franchise of portable consoles topped 100 million.

The company released its next-generation handheld console, the DSi, in Japan last November, and Iwata said total sales have so far have reached 2 million.

The DSi will launch April 3 in Europe and April 5 in the United States.

Nintendo's DS competes with Sony's PlayStation Portable. In February, the DS sold 588,000 units compared with 199,000 for the PSP, according to research group NPD.

However, Nintendo and PlayStation are seeing increased competition from Apple Inc's iPhone and iPod Touch. The Apple App Store has thousands of games that can be easily downloaded, and third-party developers are hard at work adding new titles every day.

(Reporting by Gabriel Madway; Editing by Edwin Chan, Richard Chang)

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