The United Kingdom Defence Secretary Gavin Williamson on Thursday accused the Russian military of carrying out cyber attack that targeted Ukraine and spread across Europe in 2017, The Guardian reported.

“We have entered a new era of warfare, witnessing a destructive and deadly mix of conventional military might and malicious cyber attacks,” Williamson said. “Russia is ripping up the rulebook by undermining democracy, wrecking livelihoods by targeting critical infrastructure and weaponising information...We must be primed and ready to tackle these stark and intensifying threats.”

In a statement, the UK Foreign Office asked “Russia to be the responsible member of the international community it claims to be rather then secretly trying to undermine it”.

Russia, however, denied the accusations. “We categorically dismiss such accusations, we consider them unsubstantiated and groundless,” Kremlin Spokesperson Dmitry Peskov said. “It is not more than a continuation of the Russophobic campaign which is not based on any evidence.”

The computer virus – an earlier variant of ransomware called Petya – spread through a hacked version of a major accounting program that is widely used in Ukraine. India’s largest container port, Jawaharlal Nehru Port Trust, also fell victim to it and had to shut operations in one of its three terminals. Several companies and government institutions across the globe also fell prey to the attack that began in Ukraine.

Ukraine’s state power distributor, Kiev’s main airport, the National Bank of Ukraine and other firms were the first to report the cyber attack. Chernobyl nuclear plant workers had to resort to manually monitor radiation levels after its computers were targeted.

But unlike the WannaCry ransomware, which demanded money from the computer users it had affected, NotPetya was coded in a manner that even if users had paid up, their data would never have been recovered.