'Project Shield' allows Google to absorb the bad traffic in a DDoS attack and act as a "shield" for websites, allowing them to continue operating and defend against these attacks.

"As of today, over 150 websites in Ukraine, including many news organisations, are using the service. We encourage all eligible organisations to register for Project Shield so our systems can help block these attacks and keep websites online," said Shane Huntley, Threat Analysis Group at Google.

In the last 12 months, Google's Threat Analysis Group (TAG) has issued hundreds of government-backed attack warnings to Ukrainian users alerting them that they have been the target of government backed hacking, largely emanating from Russia.

"Over the past two weeks, TAG has observed activity from a range of threat actors that we regularly monitor and are well-known to law enforcement, including FancyBear and Ghostwriter," the company said in a statement late on Monday.

This activity ranges from espionage to phishing campaigns.

'Mustang Panda' or 'Temp.Hex', a China-based threat actor, targeted European entities with lures related to the Ukrainian invasion.

Targeting of European organisations has represented a shift from Mustang Panda's regularly observed Southeast Asian targets, said Google.

"We continue to see DDoS attempts against numerous Ukraine sites, including the Ministry of Foreign Affairs, Ministry of Internal Affairs, as well as services like Liveuamap that are designed to help people find information," Google informed.