BEIJING (Reuters) - The iPhone 6 will be sold in China from Oct 17, after rigorous regulator scrutiny led to Apple Inc (>> Apple Inc.) reassuring the Chinese government that the smartphones did not have security "backdoors" through which U.S. agencies can access users' data.

Apple won approval to sell the phones after also addressing risks of personal information leaks related to the operating system's diagnostic tools, China's Ministry of Industry and Information Technology (MIIT) said on its website on Tuesday.

The iPhone 6 and 6 Plus were released on Sept 19 in the United States and elsewhere, but regulatory delay meant Chinese consumers had to wait. The initial lack of a China launch date caught analysts by surprise because of Apple's repeated comments about the importance of the world's biggest smartphone market.

Apple and other American technology companies have been subject to greater scrutiny in China after former U.S. National Security Agency contractor Edward Snowden last year revealed spying and surveillance campaigns, including programmes that obtained private data through U.S. technology firms.

In July, Chinese state media accused Apple of providing user data to U.S. agencies and called for 'severe punishment'. Apple responded by publicly denying the existence of backdoors.

The notice of approval for the iPhone 6 could potentially mark the ministry's first for a specific smartphone, suggesting Apple is subject to more scrutiny than its peers in a year in which the U.S. tech giant will release a new phone on all three of China's major mobile networks for the first time.

BACKDOORS

The MIIT said it conducted "rigorous security testing" on the iPhone 6 and held talks with Apple on the issue, and that Apple shared with the ministry materials related to the potential security issues.

One of the concerns the MIIT raised was over a third party's ability to take control of a computer that had been given trusted access to the phone by a user. They also queried Apple on the ability of staff repairing iPhones to access user data through background services.

Apple told the MIIT it had adopted new security measures in its latest smartphone operating system, iOS 8, and promised that it had never installed backdoors into its products or services to allow access for any government agency in any country, the MIIT said.

Apple earlier this month was hiring a head of law enforcement in Beijing to deal with user data requests from China's government, after it last month began storing private data on Chinese soil for the first time.

1.27 BILLION SUBSCRIBERS

With regulatory approval from the world's largest smartphone market, analysts expect the iPhone 6 and 6 Plus to sell well in China, where many people prefer phones with larger screens.

The phone will be made available on all three of China's state-owned wireless carriers: China Mobile Ltd (>> China Mobile Ltd.), China Unicom Hong Kong Ltd (>> China Unicom (Hong Kong) Limited) and China Telecom Corp Ltd (>> China Telecom Corporation Limited). Together, the three had more than 1.27 billion mobile subscribers in August.

"iPhone 6 and iPhone 6 Plus customers will have access to high-speed mobile networks from China Mobile, China Telecom and China Unicom," Apple Chief Executive Tim Cook said in a press release on Tuesday.

The iPhone 6 will be available in gold, silver and grey with a suggested retail price of 5,288 yuan ($860.16) for the cheapest model with 16GB of storage. The iPhone 6 Plus, in the same colours, will be 6,088 yuan ($990.29) for the cheapest model, also with 16GB of storage. The most expensive iPhone 6 Plus with 128GB storage will be 7,788 yuan ($1,266.82).

The phones will also be available online and by reservation from Apple stores.

Apple sold a record 10 million iPhone 6 handsets in the first weekend after their launch, which excluded China. Last year, the U.S. tech firm sold 9 million iPhone 5S and 5C models in 11 countries, including China, in the same period.

The Cupertino, California-based company said iPhone sales in China grew 50 percent during in April-June from a year earlier, effectively salvaging an otherwise lacklustre quarter. The strong sales came despite signs that Chinese consumers were waiting for the next-generation iPhone 6, analysts said.

(Additional reporting by Beijing Newsroom; Editing by Miral Fahmy and Christopher Cushing)

By Paul Carsten