In a major setback to Reliance Jio, a mobile-network operator promoted by India’s richest man Mukesh Ambani, its plea against alleged cartelization by three telecom operators has been rejected by the Supreme Court.

The apex court on Wednesday rejected the Competition Commission of India’s plea to investigate charges of cartelization by Vodafone India, Idea Cellular and Bharti Airtel. The CCI had approached the Supreme Court to challenge an earlier judgment passed by the Bombay High Court, The Economic Times reports.

The Bombay High Court in September ruled that the CCI doesn’t have the jurisdiction to order an investigation when there is a sector-specific regulator – the Telecom Regulatory Authority of India.

In November 2016, Reliance Jio filed a complaint with the CCI alleging that the three telephone companies were abusing their dominant positions to prevent it from accessing points of interconnection. Hence its customers were not able to connect with the customers of the three companies.

The CCI in May 2017 ordered an investigation into allegations of cartelization and abuse of dominance by the three telecom companies. They in turn approached the Bombay High Court to fight the CCI order.

Reliance Jio Infocomm, which began operations in 2016, has disrupted India’s mobile phone services sector by offering prolonged free voice and data plans. This led to the exit of players such as Tata Teleservices (the telecom arm of Tata Group) and Uninor, the Indian unit of Norwegian company Telenor.

The predatory competition also led to the merger of India’s second- and third-largest telecom players, Vodafone India and Idea Cellular.