After days of disruptions affecting networks worldwide, a top US official said the number of computers affected had reached 300,000, but that infection rates had slowed.

Washington: Security researchers investigating the massive cyberattack campaign that sparked havoc in computer systems world-wide have reported signs of a possible North Korean link, but Europe’s cross-border police agency said on Tuesday that it was “too early” to draw a connection.

After days of disruptions affecting networks worldwide, a top US official said the number of computers affected had reached 300,000, but that infection rates had slowed.

In the first clues of the origin of the massive ransomware attacks, Google researcher Neel Mehta posted computer code that showed similarities between the “WannaCry” malware and a vast hacking effort widely attributed to Pyongyang.

The code used in the latest attack shared many similarities with past hacks blamed on the North, including the targeting of Sony Pictures, said Simon Choi, director of Seoul Internet security firm Hauri.

“I saw signs last year that the North was preparing ransomware attacks or even already beginning to do so, targeting some South Korean companies,” he told AFP.

Isolated, nuclear-armed North Korea is known to operate an army of thousands of hackers operating in both the North, and apparently China, and has been blamed for a number of major cyberattacks.