The Kremlin said on Thursday that Telegram founder Pavel Durov's case should not turn into "political persecution" after a French judge put the Russian-born tech entrepreneur under formal investigation.

The judge said he was suspected of complicity in running an online platform that allows illicit transactions, images of child sex abuse and drug trafficking. He is also being investigated for alleged money laundering and the refusal to cooperate with judicial authorities.

A lawyer for Durov said it was "totally absurd" to suggest the head of a social network was responsible for any criminal acts committed on the platform.

"I don't think we should continue making any judgements now," Kremlin spokesman Dmitry Peskov told reporters. "We have already said that he is a French citizen, he has everything needed to organize his legal defense.

"The main thing is that what is happening in France does not turn into political persecution. We know that the president of France has denied any connection (of the case) with politics, but on the other hand, certain accusations are being made. We will see what happens next."

French President Emmanuel Macron has said that there was no political motive in Durov's detention.

Peskov also confirmed that Durov still holds Russian citizenship and said that Moscow would be ready to assist him, if necessary, as it would any Russian citizen.