North Korea's Lazarus Group carried out the WannaCry attacks that affected hundreds of thousands of computers across the UK earlier this year.
The ransomware incident impacted 300,000 computers in 150 countries including 48 NHS trusts, as well as O2 owner Telefonica, Nissan and Renault in May. In October, UK security minister Ben Wallace MP said the government believed the attack came from North Korea.
"The UK’s National Cyber Security Centre assesses it is highly likely that North Korean actors known as the Lazarus Group were behind the WannaCry ransomware campaign – one of the most significant to hit the UK in terms of scale and disruption," said Lord Ahmad, the minister for cyber.
"We condemn these actions and commit ourselves to working with all responsible states to combat destructive criminal use of cyber space. The indiscriminate use of the WannaCry ransomware demonstrates North Korean actors using their cyber programme to circumvent sanctions.
"International law applies online as it does offline. The United Kingdom is determined to identify, pursue and respond to malicious cyber activity regardless of where it originates, imposing costs on those who wish to attack us in cyberspace. We are committed to strengthening coordinated international efforts to uphold a free, open, peaceful and secure cyberspace."