Samsung Electronics Co has filed patent lawsuits against Apple over the U.S. firm's iPhone and iPad in a tit-for-tat case after Apple claimed Samsung's smartphones and tablets slavishly copied its products.

Apple filed a lawsuit last Friday alleging Samsung violated patents and trademarks of its iPhone and iPad, as the popular gadgets are being threatened by the fast rise of rival devices based on Google's free Android operating system.

The legal battle between Apple and Samsung could jeopardize business ties between the two technology companies, as the Cupertino, California-based company depends heavily on Samsung for components such as chips and LCD displays.

Operating systems have emerged as the key battlefield for dominance of the world's smartphone market.

Android became the most popular smartphone software in the United States in the three months ending in February, ahead of Apple and Research in Motion, according to a recent survey by research firm comScore.

Samsung is one of the fastest growing smartphone makers on the back of the Android boom and has emerged as Apple's strongest competitor in the tablet market, with models in three sizes.

COUNTER LAWSUITS

Samsung said in a statement Friday that Apple's iPhone and iPad infringe Samsung's 10 mobile technology patents and it called for Apple to stop infringing its technology and compensate the company.

Samsung said the suits, filed in South Korea, Japan and Germany, involved 10 alleged infringements of patents mainly involving power reduction during data transmission, 3G technology for reducing errors during data transmission, and wireless data communication technology.

Samsung is responding actively to the legal action taken against us in order to protect our intellectual property and to ensure our continued innovation and growth in the mobile communications business, the statement said.

Global technology companies are locked in a web of litigation as they try to defend their shares of the booming tablet and smartphone market.

Strong sales of the iPhone and iPad translate into more revenue for Samsung. Apple was Samsung's second-biggest client after Japan's Sony Corp last year, bringing in around 6.2 trillion Korean won ($5.7 billion) of sales, and is widely expected to become Samsung's top client this year.

The battle comes ahead of Samsung launching a new version of its successful Galaxy S smartphone next week in Korea, a key product for the world's No.2 handset maker to meet its target of 60 million units of smartphone sales this year.

Shares in Samsung, Asia's biggest technology company with a market value of $140 billion, fell 2.5 percent by 0410 GMT after three consecutive sessions of gains, versus a 0.2 percent fall in the broader market.

($1 = 1080.950 Korean Won)

(Editing by Ken Wills and Anshuman Daga)

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