Ukrainian police on Tuesday seized the servers of an accounting software firm suspected of spreading a malware virus which crippled computer systems at major companies around the world last week, a senior police official said.
The head of Ukraine's Cyber Police, Serhiy Demedyuk, told Reuters the servers of M.E.Doc - Ukraine's most popular accounting software - had been seized as part of an investigation into the attack.
Though they are still trying to establish who was behind last week's attack, Ukrainian intelligence officials and security firms have said some of the initial infections were spread via a malicious update issued by M.E.Doc, charges the company's owners deny.
The owners were not immediately available for comment on Tuesday.
The police move came after cyber security investigators unearthed further evidence on Tuesday that the attack had been planned months in advance by highly-skilled hackers, who they said had inserted a vulnerability into the M.E.Doc progamme.
Ukraine also took steps on Tuesday to extend its state tax deadline by one month to help businesses hit by the malware assault.