Google Inc's Android mobile operating system (OS) was the top smartphone platform in China last year, growing its market share by about 35 percent in the world's largest market for mobile phones, a Chinese technology research firm said.

At the end of 2011, Android had 68.4 percent of the smartphone OS market by the number of smartphones sold, up from 33.6 percent at the end of the first quarter of last year, Beijing-based research firm Analysys International said in a report on Tuesday.

The cementing of Android's dominance in China came at the expense of Finnish mobile phone maker Nokia whose Symbian OS saw its market share more than halve to 18.7 percent last year.

Apple Inc, whose iPhones are seeing strong demand from wealthier Chinese cities, posted a modest growth in 2011, with the market share of its iOs operating system rising from 4.1 percent in the first quarter to 5.7 percent at the end of the fourth quarter.

Apple has said that China, which has 988 million mobile phone subscribers, remains a key growth market for the company.

Android's rise also comes as smartphones become cheaper in China due to the sales initiatives of local mobile device makers ZTE Corp and Huawei Technologies, who sign contracts with Chinese telecoms companies to offer cheap Android handsets.

(Reporting by Melanie Lee; Editing by Muralikumar Anantharaman)

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