The UK government says hackers backed by Beijing were responsible for a data breach exposing the data of millions of voters.

According to TechCrunch, the breach occurred in 2021 but was not discovered until at least a year later. The attack, targeting the Electoral Commission, likely resulted in the hackers stealing the names and addresses of some 40 million voters.

Deputy Prime Minister Oliver Dowden minced no words about the UK’s response, saying the government “will not hesitate to take swift and robust actions wherever the Chinese government threatens the United Kingdom’s interests.”

For its part, China denied the accusations and promised to “resort to lawful methods” to fight cyberattacks.

“The malicious activities we have exposed today are indicative of a wider pattern of unacceptable behaviour we are seeing from China state-affiliated actors against the UK and around the world,” said Paul Chichester, director of operations at National Cyber Security Centre (NCSC). “The targeting of our democratic system is unacceptable and the NCSC will continue to call out cyber actors who pose a threat to the institutions and values that underpin our society.”