Reliance Industries Ltd said on Wednesday U.S. private equity firm Silver Lake Partners will invest US$1.02 billion in its retail business, helping the Mukesh Ambani-controlled company widen its lead as India's biggest retailer.

The move also sets the stage for a three-way battle between Asia's richest man, Jeff Bezos' Amazon.com Inc and Walmart Inc's Flipkart to rope in the Indian middle class customer, many of whom are newly adopting online purchases of food and groceries due to the COVID-19 pandemic.

In May, Reliance launched online grocery service JioMart. It has been aggressively building its retail presence through acquisitions, moving beyond its mainstay oil and gas business.

Silver Lake will get a 1.75 percent stake in Reliance Retail, giving the business a pre-money equity value of 4.21 trillion rupees (US$57.14 billion), Reliance said. Powered by Reliance's Jio tech platform, the unit owns retail businesses as varied as grocery stores and fashion chains, and operates close to 12,000 stores.

"The real competition is going to be between Amazon, Walmart and Reliance," said Harminder Sahni of retail consultancy Wazir Advisors. "Walmart is self-funded and Amazon is too, so the company to bet on now is Reliance."

Reliance, which has been on a fund-raising spree, saw its share price rise as much as 1.5 percent in a weak Mumbai market .

Silver Lake, whose portfolio includes stakes in Airbnb and Twitter Inc , has previously invested in Reliance's digital business as part of a funding round that saw the Indian company raise more than US$20 billion from investors including Facebook Inc and Alphabet Inc's Google.

KKR & Co Inc is in advanced talks to invest at least US$1 billion in Reliance Retail, Bloomberg reported on Wednesday, citing people familiar with the matter. Reliance declined to comment on the report when contacted by Reuters.