U.S. and British officials warned on Tuesday of a growing cyber threat from China, with the White House cyber director saying Beijing was capable of causing havoc in cyberspace and a UK spy agency chief warning of an "epoch-defining" challenge, Paralel.Az reports citing Reuters.

Anxiety has been increasing in the United States and Europe about alleged Chinese cyber and espionage activity, but Beijing has denied the accusations.

"China poses a genuine and increasing cyber risk to the UK," Anne Keast-Butler, director of Britain's Government Communications Headquarters (GCHQ) eavesdropping agency, told a security conference in the central English city of Birmingham.

She said the response to Beijing's activities was GCHQ's top priority, and that coercive and destabilising actions by China threatened international norms.

Prime Minister Rishi Sunak said on Monday Britain faced a threat from "an axis of authoritarian states like Russia, Iran, North Korea, and China", and British prosecutors charged three men with assisting Hong Kong's foreign intelligence service in Britain. China dismissed the case as a fabrication.

Britain said on Tuesday it had summoned China's ambassador to say cyberattacks and reports of espionage links were not acceptable.

Keast-Butler, who was appointed GCHQ chief last year, echoed Sunak in saying the next few years would be dangerous and transformational.

"Russia and Iran pose immediate threats, but China is the ‘epoch-defining’ challenge," she said.

U.S. National Cyber Director Harry Coker told the conference that Chinese military hackers were circumventing U.S. defences in cyberspace and targeting U.S. interests at an "unprecedented scale".

"In a crisis or conflict scenario, China could use their pre-positioned cyber capabilities to wreak havoc in civilian infrastructure and deter U.S. military action," he said.

U.S. officials confronted Beijing last month about a sweeping cyberespionage campaign dubbed “Volt Typhoon” in which Chinese hackers broke into dozens of American critical infrastructure organisations, using a vast global network of compromised personal computers and servers.

FBI Director Christopher Wray suggested it was linked to China's broader intent to deter the U.S. from defending Taiwan. A Chinese foreign ministry spokesperson said Volt Typhoon was unrelated to China's government.

The arrest of alleged Chinese spies, and accusations Chinese state-backed hackers stole data from Britain's elections watchdog and carried out surveillance operations, have increased strains in relations between Britain and China.

Sunak said last month Chinese state-affiliated actors had conducted "malicious cyber campaigns" against British lawmakers and British media, citing government sources, said China was behind a hack on the British armed forces' payments system. Beijing said the accusations were absurd.

Chinese foreign ministry spokesperson Wang Wenbin told a press conference on Tuesday that Britain had repeatedly hyped allegations about Chinese spies and cyberattacks.