Russian web users are reporting problems accessing online services as a result of the authorities' bid to block the Telegram messaging app.
Russia's media regulator has blocked more than 4 million IP addresses after a court approved its request to shut the app down.
Telegram is reportedly using the addresses to get around the block.
Retailers, online games and another message service - Viber - are also said to have been affected.
Media regulator Roskomnadzor head Alexander Zharov said on Tuesday that his agency informed Google and Amazon that it had blocked IP addresses on the companies' cloud services in an effort to implement the ban on Telegram.
A Moscow court on Friday ordered the block at Roskomnadzor's request after the app refused to hand over encryption keys used to scramble messages.
Russia's Federal Security Service, or FSB, claims the app can be used by terrorists.
Telegram says the way the app is made means the service itself does not have access to the encryption keys.
In a statement on Monday, Telegram founder Pavel Durov said the block was unconstitutional, as it infringed Russians' right to privacy of correspondence, and vowed to help users continue using the service.
He later added that fewer than 7% of Telegram's users are in Russia but that it was "personally" important for him to help them.
Mr Durov said he was giving out bitcoin funding to people running virtual private networks (VPN), which can be used to circumvent the ban, and was prepared to "donate millions of dollars".
Roskomnadzor started implementing the court's decision on Monday by ordering internet service providers to block Telegram.
The regulator has also asked Apple and Google to pull Telegram from their Russian app stories.
But some Russian Telegram users report still being able to use the app, even without using a VPN.
The Russian technology site Akket.com reports that the messenger has begun using a feature allowing it to switch IP addresses to route traffic through other companies' servers, including Apple, Google and Microsoft.
As of Tuesday afternoon, the number of blocked IP addresses has risen to more than 4 million, according to Fil Kulin, an IT researcher who is being widely quoted by independent Russian media.
The head of Russia's online retail association, Alexander Ivanov, told the Vedomosti newspaper that it had received complaints from nine online shops about the blocking.
Another messaging service, Viber, tweeted that its users were experiencing problems seemingly linked to "connectivity problems to Amazon Web Services in Russia".
The online games Guild Wars and World of Warships both said their users were having trouble logging on as a result of Roskomnadzor's blocking of IP addresses.
Many users of the Odnoklassniki social network say they have been unable to publish new posts or open old ones, according to the Mediazona news website.
On Tuesday, Roskomnadzor issued a statement describing as "inaccurate" reports that its activities had caused any outages.