NEW DELHI/SYDNEY - Indian billionaire Mukesh Ambani's Reliance Retail Ventures is in advanced talks with global investors to raise around $2.5 billion by the end of September, ahead of a potential stock market listing, people familiar with the matter told Reuters.

Three sources said the target fund raise of $2.5 billion is part of a combined $3.5 billion target the firm has set for itself, a part of which - $1 billion - came from Qatar Investment Authority (QIA) and was announced last month.

In an emailed statement, Reliance said "As a policy, we do not comment on media speculation and rumours.", but added "Our company evaluates various opportunities on an ongoing basis."

Reliance last month said it raised $1 billion from QIA at a $100 billion valuation for India's biggest retailer whose operations stretch from selling groceries to electronics, and include foreign partnerships with brands like Burberry and Pret A Manger.

Morgan Stanley is advising Reliance on the process, said two sources with direct knowledge. Morgan Stanley did not respond to a request for comment.

All the three sources declined to name potential investors. But the first source said Reliance was talking to at least two U.S.-based investors, while the other two sources said there was growing interest from existing foreign investors of Reliance, including some sovereign wealth funds.

The investment, if it materializes, will bolster India's status as a rare bright spot for Western private investors who are shying away from new investments in China due to the country's worsening economic outlook and geopolitical tensions.

In 2020, Reliance Retail raised $5.71 billion by selling a 10.09% stake to investors including KKR, the Saudi Public Investment Fund, General Atlantic and the United Arab Emirates' Mubadala.

Ambani said this week its 2020 fund raise valued the business at around $52 billion, and "in less than three years, the valuation of retail has almost doubled."

A fourth source with direct knowledge said two Reliance fund raise announcements were likely within two weeks, and valuation of the company would be around the same at which QIA invested -around $100 billion. That implies a potential $2.5 billion investment will be equivalent to a 2.5% stake in the company.

"Several marquee global strategic and financial investors have shown strong interest in Reliance Retail. I will update you about our progress with them in due course," Ambani said on Monday during the company's annual general meeting, without sharing further details.

Ambani said in 2019 that the group planned to list the retail business in five years.

Ambani's daughter Isha Ambani leads the retail expansion. Reliance Retail has more than 18,000 retail outlets, but also a growing e-commerce operation where it competes with the likes of Amazon and Walmart's Flipkart.

Reliance Retail reported a consolidated net profit of 91.81 billion Indian rupees ($1.11 billion) for the financial year that ended in March 2023, on revenue of 2.6 trillion rupees.

Since last year, Reliance Retail has been expanding its consumer business by acquiring dozens of small grocery and non-food brands as it targets building a consumer business generating annual sales of $6 billion within five years to challenge foreign giants like Unilever.

($1 = 82.6850 Indian rupees)

(Reporting by Aditya Kalra in New Delhi, Scott Murdoch in Sydney, and M. Sriram in Mumbai; Additional reporting by Munsif Vengattil and Dhwani Pandya; Editing by Susan Fenton)