Bharti Airtel, India’s largest mobile-phone operator, will spend $1 billion this year to develop its wireless infrastructure company, after its closest rival sold part of its tower unit to global investors.

Bharti Airtel, India’s most valuable wireless company, will consider selling a stake in the fully owned tower subsidiary, Chief Executive Officer Manoj Kohli said, claiming the unit will grow to be the world’s biggest this year. The time of the sale has yet to be decided, he said.

“We’re thinking about it,’’ Kohli said today in an interview. “We can’t specify, but we’ll definitely plan that at an appropriate time.’’

Bharti and Reliance Communications, India’s second- largest wireless company, are separating their towers, shelters, generators and battery back-ups into independent units to share equipment and cost with rivals. Reliance valued its tower assets at Rs 270 billion ($6.7 billion) when it sold 5 percent of the unit to seven international investors for about $338 million.

“A separate tower company gets a much better valuation than a single entity,’’ said Mahesh Patil, who helps manage the equivalent of $1.5 billion in equity assets at Birla Sun Life Asset Management in Mumbai. The incremental value creation in Bharti’s case could be as much as $12 billion, said Patil, who has Bharti as his largest holding.

India’s government is encouraging carriers to share their infrastructure to expand coverage in rural areas. Bharti’s tower spending is part of a plan to spend as much as $3.5 billion this year on network expansion to maintain its lead over Reliance and Hutchison Essar.

Bharti, about a third owned by Singapore Telecommunications, aims to have more than 65,000 towers by the end of March, from about 45,000 now, Kohli said. The company will share them with Hutchison Essar, controlled by Vodafone Group Plc, and Idea Cellular Ltd., owned by billionaire Kumar Mangalam Birla.

The legal process to set up an independent tower company would be completed by the end of October, Kohli said. The focus would be to cut energy costs, he added.

The sharing of towers would result in the greater spread of mobile phone services and lower costs for users as carriers pass on cost benefits to customers, a unit of UBS AG said.

UBS Securities analysts Suresh Mahadevan and Lydia Chan revised their forecast for wireless penetration in India to 65 percent by March 2016 from 52 percent, mainly on account of the sharing of passive infrastructure by rival carriers.

“This is likely to result in making the mobile services more affordable and available to end consumers,’’ Mahadevan and Chan said in a note released in April.