Encrypted messaging service Telegram suffered a major cyber-attack that originated from China, the company's CEO said Thursday, linking it to the ongoing political unrest in Hong Kong.
Many protesters in the city have used Telegram to evade electronic surveillance and coordinate their demonstrations against a controversial Beijing-backed plan that would allow extraditions from the semi-autonomous territory to the mainland.
Demonstrations descended into violence Wednesday as police used tear gas and rubber bullets to disperse protesters who tried to storm the city's parliament -- the worst political crisis Hong Kong has seen since its 1997 handover from Britain to China.
Telegram announced Wednesday that it was suffering a "powerful" Distributed Denial of Service (DDoS) attack, which involves a hacker overwhelming a target's servers by making a massive number of junk requests.
It warned that users in many regions may face connection issues.
Pavel Durov, Telegram's CEO, said the junk requests came mostly from China.
"Historically, all state actor-sized DDoS (200-400 Gb/s of junk) we experienced coincided in time with protests in Hong Kong (coordinated on @telegram)," he tweeted.
"This case was not an exception."
Telegram later announced on Twitter that its service had stabilised. It also posted a series of tweets explaining the nature of the attack.
"Imagine that an army of lemmings just jumped the queue at McDonald's in front of you -– and each is ordering a whopper," it said, referring to the flagship product of Burger King.
"The server is busy telling the whopper lemmings they came to the wrong place -– but there are so many of them that the server can't even see you to try and take your order."
- Evading surveillance -
When asked about Durov's claim the attack originated from China, foreign ministry spokesman Geng Shuang said he was not aware of the incident.
"What I can tell you here is that China has always opposed any form of cyber-attacks. China is also a victim of cyber-attacks," Geng said at a regular press briefing in Beijing.
China's cyberspace administration did not immediately respond to AFP's request for comment.
Telegram was launched in 2013, and allows users to exchange encrypted text messages, photos and videos, and also create "channels" for as many as 200,000 people. It also supports encrypted voice calls.
The firm announced last year that it had crossed 200 million monthly active users.
Encrypted messaging apps like Telegram and WhatsApp are preferred around the world by a wide variety of people trying to avoid surveillance by authorities -- from Islamic State jihadists and drug dealers to human rights activists and journalists.
Governments in recent years have devoted significant resources to try and breach or bypass the security features of these apps, according to tech firms and researchers. Some states have outright banned them.
Hong Kong is not behind China's Great Firewall, which heavily restricts internet access in the mainland -- where Telegram is blocked.
The city's special status under its handover agreement allows freedoms unseen in mainland China, but many fear they are under threat as Beijing exerts increasing influence on Hong Kong.
The current protests were sparked by fears the proposed law would allow extraditions to China and leave people exposed to the mainland's politicised and opaque justice system.