MUMBAI, March 1 (Reuters) - India's Adani Energy Solutions is planning to raise around $400 million-$500 million through a private placement of bonds for which it is in early talks with U.S. institutional investors, a company source and a banker aware of the plan said.

"The deal will materialise in the next three months and we are seeing strong interest from U.S. insurance companies and pension funds," the company source said.

It will be a private placement of Regulation-D notes with infrastructure assets as collateral, the sources added.

Regulation-D is a provision that exempts some companies from the registration requirements associated with a public offering of securities.

The company source and the banker spoke on condition of anonymity as they are not authorised to speak to the media. They said there were no bankers appointed yet.

The Adani group communications team did not immediately respond to Reuters' e-mail seeking comment.

Adani Energy Solutions, earlier known as Adani Transmission, is looking to issue longer-tenor bonds maturing in 20-30 years but has not finalised the terms of the issue yet, according to both the sources.

This will likely be the second dollar-bond offering by an Adani group company in 2024.

Adani Green Energy, a separate Adani group entity, is currently conducting roadshows for its U.S. dollar bond offering to raise $409 million. The deal is expected to be priced next week.

A report by U.S. short seller Hindenburg Research in January last year had led to a sell-off in stocks and overseas listed bonds of Adani group companies, forcing them to retreat from the foreign currency bond market and buy back $315 million of listed overseas debt securities alongside some other unlisted debt.

Since then, most of the group's foreign bonds are back above the levels they traded at before the Hindenburg report was issued, giving the companies comfort to look at a fresh issues of dollar bonds. (Reporting by Bhakti Tambe; Editing by Muralikumar Anantharaman)