The agency did not name the companies affected, although German postal and logistics company Deutsche Post earlier said its systems in Ukraine had been affected. [nL8N1JO452]

BSI President Arne Schoenbohm said initial indications pointed to use of the Petya malware, which utilised the same weaknesses used in the WannaCry ransomware attack that caused global disruption in May.

BSI urged companies to report any computer security issues to authorities and to refuse any request for ransom payments. It also called for companies to take digital risks seriously and invest now in increased cyber security.

Schoenboehm said a software patch available from Microsoft could have prevented infections in many cases, although Petya also used an administrative tool in internal networks that attacked even systems that have been patched.

(Reporting by Andrea Shalal; Editing by Joseph Nasr)