(Reuters) - Ukraine's leading mobile operator Kyivstar has allocated $90 million to deal with a suspect Russian cyberattack on its services and said it had hit its growth.

The hack, described by its CEO as the biggest cyberattack on telecoms infrastructure in the world, struck Kyivstar in December, damaging infrastructure and disrupting mobile phone signals for millions of Ukrainians.

"Before the cyberattack, we were moving with an increase of 11%-12% quarter-on-quarter in 2023. The cyberattack ate up about 3% of annual growth," CEO Oleksandr Komarov told the Interfax-Ukraine news agency.

He gave no additional detail about what aspect of growth that referred to. Kyivstar did not immediately reply to a request for comment.

Komarov said the mobile operator allocated 3.6 billion hryvnia ($90.76 million) to deal with the aftermath of the attack.

It went towards repairing damage as well as on strengthening the system and funding a loyalty program for clients.

Kyivstar, owned by Amsterdam-listed mobile telecoms operator Veon, has 24.3 million mobile subscribers, as well as more than 1.1 million home internet subscribers.

Kyiv's then-cyber spy chief said at the time he was confident the attack was carried out by Sandworm, a Russian military intelligence cyberwarfare unit.

Solntsepyok, a group believed by Ukraine to be affiliated with Sandworm, claimed responsibility. Russia has not commented on the attack.

(Reporting by Yuliia Dysa; Editing by Alison Williams)