Bharti Airtel Ltd, India's top mobile phone carrier, and its smaller rival Aircel separately said on Monday they would launch Apple's iPhone 4 in India in the coming months.

Both companies declined to give specific dates for the planned launch.

Bharti and Vodafone Essar already sell earlier models of the iPhone in India.

With nearly 800 million mobile subscribers, India is the world's second-biggest market for mobile phone services and is also the fastest-growing. But smartphones are estimated to account for just over 5 percent of the mobile handset sales.

Indian carriers have recently started rolling out high-speed third-generation (3G) mobile networks, which is expected to boost sales of smartphones.

Bharti had 159 million mobile subscribers as of end-February, while Aircel had 53.5 million.

(Reporting by Bharghavi Nagaraju and Devidutta Tripathy; Editing by Aradhana Aravindan)