Ukraine said a cyberattack brought down the websites of several government agencies Friday (Jan 14).
Authorities didn't immediately comment on the source of the outage, which comes amid surging tensions with Russia due to its buildup of thousands of troops near the border.
A spokesman for Ukraine's Foreign Ministry said on Twitter that the websites were down following a massive hack and that authorities were working to restore services.
He didn't identify who might be behind the attack, which hit the site of his agency as well as those of the Agriculture and Education Ministries and the government staff. All those sites were down, some with their content replaced for a time by messages in Russian, Polish and Ukrainian.
"Ukrainian! All your personal data has been uploaded to the public network," the message said.
"All data on your computer is being erased and won't be recoverable. All information about you has become public, fear and expect the worst. This is being done to you for the your past, present and future," it said, with a reference to "historic lands."
The education ministry said that authorities - including the SBU security service and cyberpolice - were working to address the issue.
Ukraine has previously accused Russia of mounting major cyber attacks against it as relations between the two neighbours have worsened since a 2014 conflict.
In recent months, Ukraine and its allies in the US and Europe have warned that Russia could be preparing to invade as it massed about 100,000 troops near the border. Moscow denies any such plans.
A Kremlin spokesman didn't immediately respond to a request for comment on the cyber attack.
The US and its allies have warned that Russia might use hacking or other actions short of a military operation to put pressure on Ukraine. Russia denies it uses cyber weapons offensively but President Vladimir Putin has said what he called "patriotic hackers" may take it upon themselves to stand up for the country's interests online.
As tensions have mounted in recent months, the US and its allies have been working to ready a package of sanctions to respond to a potential invasion or further acts of Russian aggression, though it's not clear whether a cyber attack, if shown to be linked to Moscow, would trigger major retaliation.
Trading in the Ukrainian currency and government bonds opens after 10am in Kyiv. As of 9.59am in Moscow, the ruble was trading 0.4 per cent stronger against the dollar.
The currency posted its sharpest daily drop since October 2020 on Thursday after a senior Russian diplomat said Moscow's demands for security guarantees from the US and its allies had hit "a dead end."