Indian 4G newcomer Reliance Jio is questioning market leader Bharti Airtel’s claims of having the fastest network in the country and filed a legal notice against broadband speed testing company Ookla saying its “results are fundamentally flawed and unreliable”.

Jio wrote to the country’s Advertising Standards Council asking for Airtel’s ads to be removed, complaining Airtel’s claim is not true, is misleading and violates the council’s code, The Economic Times (ET) reported.

In a legal notice reviewed by the ET, Jio’s lawyers said Ookla falsely certified Airtel to be India’s fastest mobile carrier. The notice alleges Ookla “abused its dominance in this domain in an unethical manner by concealing true facts”.

Airtel defended its ads, noting Ookla’s findings are based on analysis of millions of internet speed tests from subscribers using its Speedtest app, the newspaper said.

Jio, which announced last month it has 100 million subscribers, has long claimed its 4G network is the country’s fastest. It said in February its average data speed, according to the Telecom Regulatory Authority of India’s speed analytics portal and other independent agencies, was 9.8Mb/s compared with a range of 4.2Mb/s to 5.9Mb/s for the other players.

The war of words over the speeds claims is just the latest clash between the two operators, following battles over Jio’s extended free offers, with Airtel accusing the newcomer of predatory pricing, and an alleged lack of access to interconnection points from the incumbent.