A former top Amazon seller in India has asked a judge to quash an antitrust investigation that found the U.S. e-commerce company and some of its sellers breached local competition laws, court records showed on Thursday.

Antitrust investigations conducted by the Competition Commission of India (CCI) have found Amazon and Walmart's Flipkart, some of their sellers and smartphone brands, violated local competition laws by giving preference to select online sellers and prioritizing certain listings, Reuters has reported.

The findings follow a Reuters investigation in 2021 which was based on Amazon's internal documents and showed the company gave preferential treatment for years to a small group of sellers on its platform, and used them to bypass Indian laws. Amazon denied any wrongdoing.

One of those sellers, Appario, which has since ceased to be a seller on Amazon, on Thursday challenged the CCI in the High Court in Karnataka state, saying the investigation report that names it must be "set aside", court records showed.

No further information on the grounds for the suit was immediately available.

The lawsuit marks the first legal challenge to the CCI investigation that started in 2020, and poses a major challenge to Amazon in India, a key market.

Appario also said in the suit that a CCI order that asked it to submit its financial statements after the investigation was completed should be quashed, according to the court's records.

Appario, Amazon and the competition regulator did not respond to requests for comment.

Amazon maintained it does not give preferential treatment to any seller and complies with all laws, but said in October 2022 that Appario will within a year cease to list products on its website.

The Reuters investigation had found that Appario was internally referred to as a "special" merchant and received discounted fees and access to Amazon global retail tools used for things like inventory management.

In 2022, the CCI raided Appario and some other sellers as part of its investigations.