China has described as "groundless" claims by the US and UK that Beijing is determined to steal their technology for competitive gain.

The heads of MI5 and the Federal Bureau of Investigation, in a rare joint address at the British intelligence service's London headquarters, warned on Wednesday of what they called Chinese commercial espionage in the West.

A spokesman for the Chinese embassy in Washington, Liu Pengyu, rejected the allegations, saying in a statement that China “firmly opposes and combats all forms of cyber attacks”, and called the accusations groundless.

“We will never encourage, support or condone cyber attacks,” he added.

Speaking to officials and business executives in Thames House, MI5 Director General Ken McCallum and FBI Director Chris Wray alleged that the threat from Chinese spies in both countries continues to grow.

McCallum said the British domestic intelligence service had sharply expanded its China-focused operations, while Wray claimed China is "set on stealing your technology, whatever it is that makes your industry tick, and using it to undercut your business and dominate your market". (Agencies)