Britain's claim that China was responsible for cyber campaigns targeting Britain is "completely unfounded and constitutes malicious slander," the Chinese embassy in Britain said in a statement on Monday.

China firmly opposes and strongly condemns this and has made a solemn protest to the British side, said the statement.

"We have firmly fought and stopped all kinds of malicious cyber activities in accordance with the law, and have never encouraged, supported or condoned cyberattacks," said the statement, noting that China is a major victim of cyberattacks.

China has always adhered to the principle of non-interference in others' internal affairs and has no interest or need to meddle in Britain's internal affairs, it said.

"The UK falsely accused China of attempting to interfere with UK democracy. This is nothing more than a publicity stunt. This is also a typical example of a thief crying 'catch thief,'" said the statement.

China has always stood against illegal unilateral sanctions and will make a justified and necessary response to this, it said.

"We strongly urge the UK to immediately stop spreading false information about China, stop such self-staged, anti-China farces, and refrain from going further down the wrong path that leads only to failure," it added.