Trafigura is preparing to sell its 24.5 per cent indirect stake in an Indian oil refining joint venture with Russia's Rosneft to an Italian group, a letter seen by Reuters shows and people familiar with the commodity trading firm's plans said.

Trafigura holds the stake in Nayara Energy, which owns India's third largest refinery, a port and a network of more than 6,000 fuel stations across India, indirectly through a 49.84 per cent holding in Singapore-based Tendril Ventures.

It plans to sell the Nayara stake to Italy's Genera Group Holding SPA, people familiar with the matter said, without giving detail on what had prompted Trafigura to sell.

"We have been informed that Trafigura proposes to sell its shareholding in Tendril to a third party; being Genera Group Holding SPA," Nayara's chief executive Alois Virag wrote in aletter to its lenders earlier this month.

Trafigura declined to comment. Genera did not respond to Reuters emails and messages seeking comment. Nayara said it could not comment on the actions of its shareholders.

It is unclear how much Trafigura's stake in Nayara, formerly known as Essar Oil, is worth.

Ownership

Nayara, which owns the 400,000 barrels-per-day (bpd) Vadinar refinery plant in the western Indian State of Gujarat, changed hands for nearly $13 billion in 2017, so the Trafigura stake then would have been worth more than $3 billion.

The other owner of Tendril is Russian investment group United Capital Partners (UCP), which also has 49.84 per cent.

Tendril's wholly-owned subsidiary, Cyprus-registered Kesani,owns a 49.13 per cent stake in Nayara Energy. Rosneft's Singapore unit also has a 49.13 per cent stake and public shareholders the remainder.

When Kesani and Rosneft bought the Nayara stakes in 2017,the sale was structured in a way to prevent Rosneftfrom acquiring a controlling stake and avoid running foul of US sanctions on the Russian oil major.

"As a result of the proposed transfer, Trafigura will ceaseto hold an indirect shareholding in Kesani and hence also in theborrower (Nayara)," Virag says in the letter seen by Reuters.

After the transfer, Genera will hold a 24.5 per cent stake inNayara, through Tendril and Kesani, the letter said.

Tendril, which shares its official address with Trafigura in Singapore, could not be reached by Reuters for comment.

Nayara Energy has written to its local and global lenders including State Bank of India, Punjab National Bank, HDFC Bank, Axis Bank, Canara Bank, ICICI Bank, Citibank and Barclays to request a no objection certificate.

Genera has meanwhile approached the anti-trust regulator Competition Commission of India (CCI) seeking permission to acquire Trafigura's stake in Nayara, sources said.

The Indian banks and CCI did not respond to requests for comment. Citibank and Barclays declined to comment.