Ukraine's Kyivstar says it is fully operational after cyber attack

KYIV (Reuters) -Ukraine's biggest mobile operator Kyivstar said on Wednesday it had restored all services within the country and abroad a week after a massive cyber attack damaged IT infrastructure and affected air raid alert systems in some parts of the country.

Services of the company, which counts more than half of Ukraine's population as mobile subscribers, were knocked out after hackers used an employee's compromised account to carry out the attack.

"We have restored all services 100% throughout Ukraine, as well as abroad... All Kyivstar services function without any restrictions," CEO Oleksandr Komarov said in televised comments.

A group called Solntsepyok, believed by Ukraine's SBU security service to be affiliated with Russian military intelligence, claimed responsibility for the attack, thanking "concerned colleagues" at Kyivstar.

The SBU has opened a criminal case.

Komarov said Kyivstar, owned by Amsterdam-listed mobile telecoms operator Veon, was cooperating with the SBU in the ongoing investigation.

"We have drawn conclusions, and quite fundamental. I believe they will apply not only to Kyivstar, but also to many companies," he added.

Mobile internet, voice and SMS services were first to be restored although there had still been some technical difficulties, including on Wednesday when voice communications were affected in several regions.

The services are now operating as usual, the company said in a separate statement on X social media platform.

It was not clear how hackers gained access to the employee's account, Kyivstar said earlier, but personal data was not compromised.

(Reporting by Pavel Polityuk, Yuliia Dysa; editing by Jason Neely, Kirsten Donovan)