Telegram founder Pavel Durov said a massive cyber-attack on his intelligence came from China.
On Wednesday, the company confirmed that it suffered a "powerful" Distributed Denial of Service attack that disrupted the services for about an hour.
In a DDos attack, hackers overwhelm the servers of a target with junk requests.
It came when protesters in Hong Kong used telegrams to coordinate demonstrations about a plan that would allow extradition to China.
Mr. Durov later tweeted that the IP addresses involved in the attack came largely from China.
China's cyberspace administration, which monitors the country's cyber policy, has not yet commented on this.
Telegram allows users to send encrypted messages, documents, videos and pictures for free.
Users can create groups for up to 200,000 people or channels for transmission to an unlimited audience. Image Caption
Its popularity has increased because the emphasis on encryption thwarts many widespread methods of reading confidential communications.
Mr. Durov's comments came in response to reports that a Hong Kong man who had been arrested as an administrator of a telegram group was being arrested for conspiracy.
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Police and protesters had been battling on Wednesday in the city to prevent the extradition of suspects to mainland China.
72 people were injured, including two men who were in critical condition.
Hong Kong is part of China on the principle of "one country, two systems", which ensures that it retains its own judicial independence own legislative and economic system.
People fear that the extradition law could bring Hong Kong more firmly under the control of China.