The founder of the Telegram messaging app, Pavel Durov, under investigation in France, said early on Friday that French authorities should have approached his company with their complaints rather than detaining him.

Pavel Durov, writing on his Telegram channel in his first public comments since his detention last month, denied any suggestion the app was an "anarchic paradise".

He said the investigation into the app was surprising in that French authorities had access to a "hot line" he had helped set up and they could have contacted Telegram's EU representative at any time.

"If a country is unhappy with an Internet service, the established practice is to start a legal action against the service itself," he wrote.

"Using laws from the pre-smartphone era to charge a CEO with crimes committed by third parties on the platform he manages is a misguided approach."

Telegram, he said, was not perfect, but he denied any abuse associated with the app.

"But the claims in some media that Telegram is some sort of anarchic paradise are absolutely untrue," he wrote. "We take down millions of harmful posts and channels every day."

Durov, born in Russia but now a French national, was detained late last month in France amid an investigation into crimes related to child pornography, drug trafficking and fraudulent transactions associated with the app.