A French judge has been appointed to investigate the controversial $1 billion sale of Rafale fighter jets to India in 2016 over “corruption allegations,” the national financial prosecutor’s office (PNF) said Friday.

The 7.8 billion euro ($9.3 billion) contract for 36 aircraft between the Indian government and France’s Dassault has long been plagued by corruption allegations.

Initially, PNF refused to investigate the sale, prompting French investigative website Mediapart in September 2016 to accuse PNF and France’s anti-corruption agency of “covering up” suspicions surrounding the deal.

In April, Mediapart alleged that a middleman who helped Dassault conclude the sale received “millions of euros in hidden commissions,” some of which may have gone to Indian officials as bribes.

Dassault responded that the group’s audits found no irregularities.

Based on this information, Sherpa, a French NGO specializing in financial crime, filed a formal complaint about “corruption” and “influence peddling,” which led to the appointment of an investigating magistrate to look into the transaction.

Sherpa had already called for an investigation into the transaction in 2018, but the PNF took no action.

In its first complaint, the NGO condemned Dassault’s choice of Reliance Group as its Indian partner. The latest is a conglomerate led by billionaire Anil Ambani, a close confidant of Prime Minister Narendra Modi.

Dassault was awarded a contract in 2012 to supply 126 aircraft to India and was in talks with Hindustan Aeronautics Limited (HAL).

By March 2015, negotiations were nearly complete, Dassault said.

In April that year, after Modi’s official visit to France, talks came to an abrupt halt, to everyone’s surprise.

Reliance Group, which has no experience in aviation, replaced HAL and signed a new contract for 36 aircraft.

At the time of the negotiations, in January 2016, Reliance was financing a film co-produced by Julie Gayet, the partner of then-President François Hollande.

Sherpa believes it could be an “influence peddling.”

Hollande said there was no conflict of interest and that France had no say in Dassault’s partner in India.

French newspaper Le Monde also revealed that France had canceled a €143.7 million tax adjustment against a French company owned by Reliance in 2015 while the deal was being negotiated.