Russia’s internet watchdog has blocked an estimated 16m IP addresses in a massive operation against the banned Telegram messaging app that could set a new precedent for Russian online censorship.

The “battle for Telegram” pits one of Russia’s most popular messaging apps – with more than 13 million users – against the internet censor Roskomnadzor, in a public cat-and-mouse game to block traffic that has put the agency’s reputation on the line.

Telegram is widely used by the Russian political establishment, and prominent politicians and officials have openly flouted or criticised the ban. Data from the app showed several Kremlin officials had continued to sign in on Tuesday evening, four days after a court ordered the service to be blocked over alleged terrorism concerns.

Edward Snowden, the NSA whistleblower living in Russia, also came out in support of Telegram’s founder, Pavel Durov, on Tuesday, tweeting: “I have criticized @telegram’s security model in the past, but @Durov’s response to the Russian government’s totalitarian demand for backdoor access to private communications – refusal and resistance – is the only moral response, and shows real leadership.”

Backed by Russia’s federal security service (FSB) and a court decision, Roskomnadzor has pushed forward, banning subnets, totalling millions of IP addresses, used by Amazon Web Services and Google Cloud, two hosting sites that Telegram switched to over the weekend to help circumvent the ban.

Several other Russian companies have become collateral damage, with users reporting outages for the social network Odnoklassniki, the Viber messenger app, an online English language school, a courier service and others.

While the estimated 16m IP addresses are still a very small portion of the total number used, the effort to shut down a messaging service such as Telegram through brute force remains unprecedented.

Andrei Soldatov, the co-author of The Red Web, an authoritative account of internet surveillance in Russia, said the campaign showed a no-holds-barred approach unconcerned with political fallout.

“They’ve decided the political costs of blocking Telegram and millions and millions of IP addresses used by Amazon and Google are not that high,” Soldatov said. “Once you cross the line, you can do anything. I think it means that they could move on from Telegram to big services like Facebook and Google.”

The contest has taken place in public, with Roskomnadzor officials and Telegram employees trading barbs and estimates of the service’s functionality, as Russian media and bloggers chart the fallout.

The Roskomnadzor head, Aleksandr Zharov, told the independent Russian business outlet the Bell: “Telegram’s degradation is now at 30%.”

But data published by the Bell suggested views of Russian-language channels on the service had risen by 30m, or 17%, on the day it was blocked.

So far, neither Amazon nor Google have commented publicly on the blocking of their hosting’s IP addresses.

Durov, the Russian tech entrepreneur who founded Telegram, said the effect on Telegram’s operations was minimal. He also noted that users could continue to use the service if they installed Virtual Private Networks, or used internet proxies, on their devices.

“Despite the ban, we haven’t seen a significant drop in user engagement so far, since Russians tend to bypass the ban with VPNs and proxies,” Durov, who now lives outside Russia, wrote in a message to Telegram users on Tuesday evening.

He also announced he would donate millions of dollars in cryptocurrency to companies helping to promote VPNs and proxies, calling it the “digital Resistance”.

Russia last year also passed legislation forcing VPNs to block sites blocked by the government. Many have not complied, and the law has not been widely enforced.