Prime Minister Rishi Sunak said on Monday the UK would do what was necessary to protect itself from a cyberattack by China, as Beijing-linked hackers were expected to be accused of recent security breaches.

Deputy prime minister Oliver Dowden is due to make a statement about the hackings of the Electoral Commission and parliament at 1530 GMT, with sanctions imposed on those allegedly behind them.

Sunak talked tough on China as he bid to become leader of the ruling Conservative party in 2022 but has since moderated his stance while in office.

He said Monday that the government had "invested significantly" in capabilities and tools to protect the country, calling China "an economic threat to our security and an epoch-defining challenge".

"We will always do what is required to keep our country safe," he told the BBC.

The Electoral Commission breach in August 2021 saw the personal details of about 40 million UK voters compromised.

Four lawmakers who have repeatedly called for tougher action against China were also called in for a security briefing after the attacks.

China's foreign ministry spokesperson Lin Jian on Monday dismissed the claims, saying Beijing had been "resolute" in curbing and severely striking down "all kinds of malicious cyberactivities".

"The issue of tracing cyberattacks is highly complex and sensitive," he added.

"When investigating and determining the nature of cyberincidents, there should be ample objective evidence, instead of smearing other countries without factual basis, let alone politicising cybersecurity issues."

The UK has for several years been increasingly at loggerheads with Beijing over civil and human rights crackdowns in China and the former British colony Hong Kong.

Ties have been strained further by the UK blocking access to Chinese companies in key British infrastructure projects, including in the nuclear and IT fields.

Last year a UK parliamentary researcher was arrested under the Official Secrets Act on accusations of spying for China.

In 2022, the UK domestic intelligence service MI5 said that a female Chinese government agent had been "engaged in political interference activities on behalf of the Chinese Communist Party, engaging with members here at parliament".

In July this year, parliament's intelligence and security committee claimed that China was targeting the UK "prolifically and aggressively" and that the government did not have the "resources, expertise or knowledge" to deal with it.

China has consistently denied accusations of espionage and other wrongdoing.