Ukrainian government websites have been temporarily taken down in the aftermath of a wave of digital attacks amidst Russia's invasion of Ukraine, a government official said Monday.

Several embassy websites - including the Ukrainian Ministry of Foreign Affairs and the Ukrainian Embassy to the United States - were inaccessible amid reports of widespread denial of services attacks against Russian and Ukrainian sites.

Victor Zhora, deputy director of Ukraine's State Service of Special Communication, said in a message distributed to journalists that the sites were "temporarily down" after "the latest cyberattacks", and that the foreign ministry's IT infrastructure was being moved to a new location.

It was not immediately clear when the sites would be restored. Zhora said it was more important "to resist the aggressor and save lives during these challenging times".

The news that the sites had been taken down came as Ukrainian officials publicly preparing for cyberattacks of their own.

Earlier on Monday, Zhora's agency publicly solicited Russian passwords and details of Russian cyber weaknesses, posting an appeal on Twitter for information that could help hackers break into Russian networks.

"If you possess any information regarding vulnerabilities in Russian cyber defences (bugs, backdoors, credentials), please report it," Ukraine's State Service of Special Communications and Information Protection said in a tweet.

Ukrainian officials did not respond to a message seeking further comment on the appeal, but they have increasingly called on hackers worldwide to help fight Russia's invasion.

Over the weekend Vice Prime Minister Mykhailo Fedorov said Ukraine was creating an "IT army" to combat Russia's digital intrusions - and a Telegram channel devoted to the effort has since made repeated claims of knocking Russian websites offline through denials of service.

Russia calls its action in Ukraine a "special military operation" to disarm the country.

Last week, Ukraine called on its hacker underground to help protect critical infrastructure and conduct cyber spying missions against Russian troops.