The Russian Central Election Commission has reported a distributed denial-of-service (DDoS) attack on its website via its Telegram account.
Deputy Chairman of the Commission Nikolay Bulaev previously stated that he had received reports of an incoming attack that could count 240,000 queries per second. Bulaev said that someone is trying to "test the strength of the system".
Bulaev added that, according to preliminary data, the attack was launched from the US, the UK, Ukraine, and a number of other nations.
The attack comes as the nation is holding a vote on constitutional amendments that were announced in January.
The vote was originally scheduled for April, but had to be moved to a later date due to the coronavirus pandemic.
While the official date of voting is 1 July, Russian citizens began voting on Thursday in order to minimise the number of people at polling stations to avoid the spread of COVID-19.
The amendments will alter the structure of presidential and parliamentary power and will also nullify the current president's term count, allowing Putin to run for the post again.