The two arch rivals are bracing for a full-blown battle with the expected rollouts of the two key models coming as they lock horns in a high-stakes patent trial in the United States.

"We plan to unveil the next Galaxy Note at the Samsung Mobile Unpacked event in Berlin on August 29," a Samsung spokesman said on Friday, without elaborating. The event will take place two days before the opening of Europe's biggest consumer electronics trade fair IFA.

South Korean media reports speculate the new Galaxy Note may feature an unbreakable, 5.5-inch display - slightly larger than the current one - as well as a faster processor and a much better camera.

Samsung, once a laggard in the smartphone market, overtook Apple last year to become the world's largest smartphone maker. The South Korean firm is looking to defend its supremacy by refreshing its line-up ahead of the launch of the fifth version of Apple's iPhone, widely expected to be released in October.

Samsung launched its flagship Galaxy S III in May, while Apple is planning a major product launch on Sept 12, stoking speculation the company may announce the sale of its redesigned iPhone.

Samsung is estimated to have increased smartphone shipments to 50.5 million in the April to June quarter of this year, nearly double the 26 million iPhones sold.

Apple shipments in the June quarter tumbled 26 percent on the previous quarter as the European economy sagged and consumers held off on buying ahead of the release of the iPhone 5.

The two tech titans also started a trial in a U.S. court this week in a patent battle triggered by Apple's lawsuit last year claiming that Samsung slavishly copied Apple's smartphones and tablets. Samsung has countersued.

(Reporting by Hyunjoo Jin; Editing by Richard Pullin)

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