MUMBAI/NEW DELHI, March 15 (Reuters) - A little-known Indian company, Qwik Supply Chain, which purchased $50 million worth of bonds for political donations via an opaque scheme is affiliated to billionaire Mukesh Ambani's Reliance group, regulatory filings show.

India's Election Commission on Thursday made public details of companies and individuals who bought electoral bonds, which permitted unlimited, anonymous political donations since 2018.

The Supreme Court of India banned these instruments on Feb. 15, calling them "unconstitutional" and saying contributions "by companies are purely business transactions made with the intent of securing benefits in return."

Qwik Supply Chain was the third largest donor using these bonds, following Indian lottery firm Future Gaming, which paid $165 million, and infrastructure company Megha Engineering which bought bonds worth $117 million, the Election Commission data showed.

While the data released revealed donor identities, it does not show which party they donated to. Corporate funding is a sensitive subject in India and Thursday's disclosure has become a hot topic as critics often say such bonds helped companies hide their donations to avoid any potential allegations of winning favours from a ruling party.

Qwik Supply Chain, headquartered near Mumbai, bought bonds worth 4.1 billion rupees ($50 million) in 2022 and 2023, the data shows.

The company's latest financial statement for the year to March 2023 filed with the Indian government shows that at least three companies - Reliance Group Support, Reliance Fire Brigade and Reliance Hospital Management - together own 50.04% of its stake.

The three companies have the same office addresses as other Reliance businesses in Mumbai, corporate filings show.

Reliance said late on Thursday that Qwik "is not a subsidiary of any Reliance entity", without elaborating. It did not respond after Reuters shared the regulatory papers and shareholding details linking it to Reliance.

Qwik's company secretary Anushree Bhargava, who has a Reliance Industries Ltd corporate email address in Qwik's regulatory filings, also did not respond to a request for comment.

India's Ministry of Corporate Affairs, where regulatory filings are made, did not immediately respond to queries.

LOGISTICS COMPANY

A source with direct knowledge said Qwik is Reliance's internal logistics and supply chain company which works closely with Reliance's retail unit.

Qwik generated revenue of 157 billion rupees ($1.9 billion) for the year to March 2023, according to its annual financial statement filed to the Indian government.

North Eastern Carrying Corporation, an Indian logistics company, in 2022 told Indian stock exchanges in a filing that it had won a work order from Qwik, which it described as "a subsidiary of Reliance Industries".

Prime Minister Narendra Modi's Bharatiya Janata Party was the biggest recipient of the electoral bond scheme, receiving 55% of the 120.1 billion rupees worth of bonds between January 2018 and January 2024 from unnamed donors.

Other top corporate buyers of the bonds include mining giant Vedanta and Indian telecom group Bharti Airtel, data released on Thursday showed. (Reporting by Aditya Kalra, Krishn Kaushik and Dhwani Pandya; Additional reporting by Arpan Chaturvedi and Chris Thomas; Editing by Susan Fenton)