Logitech, the world's largest computer mouse maker, cut its full-year outlook for the third time after third quarter sales and profit were hit by euro weakness and as computer systems require become less dependent on peripheral components.

It was the latest in a string of profit warnings for the maker of webcams, speakers and keyboards, over the last year as the company struggles with a weak economic environment.

Logitech now expects to achieve full-year sales of some $2.3 billion, down from $2.4 billion and operating income of around $60 million, compared to its previous forecast of $90 billion.

Since we last provided our outlook for fiscal year 2012 at the end of October, several factors have changed, said Logitech chairman and acting chief executive Guerrino De Luca in a statement on Thursday.

Most significantly, the euro has weakened considerably during the last three months. In addition, webcams and remotes continue to be impacted more than expected by product portfolio and market weakness.

By 4:02 a.m. ET shares in Logitech were down 13.56 percent, underperforming a flat Swiss market.

The biggest disappointment is the guidance revision for full-year 2012 ... With that we fear confidence in management is eroding further, Vontobel analyst Michael Foeth said in a note.

In October, De Luca promised no more bad news and the company appeared to have weathered the worst, bouncing back into the black in the second quarter after issuing two profit warnings.

As well as euro weakness, Logitech is grappling with a shift towards stand-alone mobile computing systems that do not require peripheral interfaces.

The fact that new devices like tablet PCs or smartphones function like a camera or already have keyboards integrated, is likely to raise questions about the future course of growth, Wegelin analysts said.

Logitech's third-quarter sales fell 5 percent to $715 million, while net income dropped 15 percent to $55 million.

Its results contrast with stellar earnings for Apple Inc on Tuesday after sales of its iPhone and iPads skyrocketed in the quarter, smashing Wall Street expectations.

(Reporting by Caroline Copley; Editing by Jodie Ginsberg and Hans-Juergen Peters)

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