Bollywood superstar Shah Rukh Khan has been chosen as the brand ambassador by billionaire Mukesh Ambani for his telecom venture, Reliance Jio, which will launch its 4G services on 27 December. Initially, the 4G services will be for the company's employees.

However, the commercial launch of Reliance Jio 4G services is expected around March-April next year.

"I am their brand ambassador. Mukesh 'bhai' explained it to me. Actually it's his children who are doing it. All the three are very close to me," Khan said in an interview with ETV.

Earlier, the Bollywood actor was the brand ambassador for India's top telecom operator Bharti Airtel.

Khan and musician AR Rahman will host the Reliance Jio 4G launch function to be held on Sunday.

Reliance Jio delayed the launch twice to improve the services, the "Dilwale" actor said.

"They deferred it twice, because they felt there is work still left in end use. 27th will be soft launch and in March-April we will do more. So I think Jio will be revolutionary. Not just for India. It will change things around world for India," Khan said.

"Shah Rukh Khan is launching Jio on 27th December," a Reliance Jio spokesperson told PTI.

Sunil Bharti Mittal, Bharti Airtel's founder and chairman, had recently said that Reliance Jio was "using" Airtel's two icons -- Khan and Rahman -- for the soft launch.

Last week, brokerage firm CLSA said that Reliance Jio's 4G launch is expected to pose significant risks to market shares of the top two telecom operators -- Bharti Airtel and Vodafone India -- as their high-value subscribers may become "early adopters" of the high-speed data services offered by the telecom arm of Mukesh Ambani's Reliance Industries.

A report by another brokerage firm, Credit Suisse, said the download speed on the network touched a peak of 70 megabits per second (Mbps) during the trial phase, but stayed in the range of 15-30 Mbps most of the time.

At a peak download speed of 70 Mbps, a user can download a Bollywood movie-size video in just 80 seconds, while it can be downloaded in a little more than three minutes at 30 Mbps and a slightly more than six minutes at 15 Mbps.