The U.S. retailer will buy a majority stake through a mix of primary and secondary share purchases.

Amazon may make bid to buy Indian e-commerce firm Flipkart, which is currently in talks with Walmart Inc for a stake sale, local daily Mint has reported.

A deal with Walmart is more likely to go through the report added.

Amazon declined to comment while Flipkart did not immediately respond to a request seeking comment.

Walmart is in talks to buy a stake of over 40 percent in Flipkart, a direct challenge to Amazon in Asia's third-largest economy.

The U.S. retailer will buy a majority stake through a mix of primary and secondary share purchases in a deal that could value Flipkart at $21 billion, the Mint report said.

The deal with Walmart is expected to aid Flipkart in its fight against Amazon, which has committed to investing $5 billion in India as it expands aggressively, including into online grocery deliveries, which analysts tip as the next big battleground for the country's e-commerce sector.

Flipkart, founded by former Amazon employees Sachin Bansal and Binny Bansal in 2007, controls nearly 40 % of India's online retail, ahead of Amazon, according to estimates by research firm Forrester.