Ukrainian internet provider Ukrtelecom is down following what is being described as the most severe cyberattack since the start of Russian's invasion into Ukraine.
The government is investigating the attack, Victor Zhora, deputy head of the State Service for Special Communications and Information Protection confirmed to Forbes.
It was not yet known whether Ukrtelecom has been hit by a distributed denial of service (DDoS) attack or a deeper, more sophisticated intrusion, Mr Zhora said.
The attack has been acknowledged by the telecommunications company in a Facebook post, and in responses to customer comments on Facebook.
A post from the company to Facebook on Monday noted there were "Temporary difficulties with installing new internet sessions in Ukrtelekomu".
"We are working to restore stable work as soon as possible," it continued.
One response to a customer complaining of services being down, said: "Good day!"
"Due to the powerful kíberataku of the enemy, we have problems with providing services.
"The contact center and Facebook are experiencing an abnormal load, so subscriber appeals are delayed. We ask you to be understanding the situation at hand."
"Kíberataku" translates to cyber attack.
According to NetBlocks, which tracks internet downtimes across the world, Ukrtelecom had been dealing with a disrupted service since this morning.
The provision of services had collapsed to “13% of pre-war levels", NetBlocks said.
NetBlocks director Alp Toker tweeted that the attack was the most significant since Russia’s invasion.
Mr Toker said the giveaway that the outage wasn't a power or cable cut was the "gradual loss of connectivity".
“The new attack has cut deep into Ukraine’s connectivity at nation scale and with extended duration and impact,” he said.
“Unlike the spate of cuts and outages in the most heated conflict zones, this one has struck the country’s national operator at its core and they appear to be struggling to mitigate the incident.”
The cyberattack is the latest in a lengthy list of attacks of this nature on Ukraine since Russia's invasion.
On the morning of Thursday February 24, large-scale cyber attacks were aimed at the Ukrainian government website.
Websites for Ukraine ’s defence, interior and foreign ministries were all targeted, leaving them slow or unresponsive.
Another attack was reported to have hit the Ukrainian government the day before.
The type of attacks that have been used against Ukraine direct junk traffic at the sites leaving them unusable, the Independent reports.
The UK government said the same type of attacks, known as distributed denial of service (DDoS), were also carried out on the Ukrainian banking system on February 15 and 16.
They said the attacks “involved the Russian Main Intelligence Directorate”.
