The Western defence alliance's Cooperative Cyber Defence Centre of Excellence (CCDCOE) added that it had also welcomed Iceland, Ireland and Japan into the fold.

"We are particularly glad to see Ukraine here with us," Estonian Defence Minister Hanno Pevkur was quoted as saying in a CCDCOE statement.

"This offers a unique opportunity to simultaneously contribute to Ukraine's defence in Russia's brutal war and learn from the cyber battlefield to improve the cyber security of all members."

Ukraine's ambassador to Estonia, Mariana Betsa, hailed the "landmark event" as "an important step on the way to Ukraine's accession to NATO".

The centre -- which now extends to NATO member states and eight additional countries -- was founded in 2008 in the Estonian capital.

At the centre, data experts from across Europe and the United States work to protect the information networks of the Western defence alliance.