A foreign ministry spokesperson said Washington and others should stop their own cyber attacks, accusing them of "political manipulation".

He added that Britain's evidence for alleging its electoral commission and MPs had been hacked was "inadequate".

The US and UK have blamed a Chinese state-run cyber unit for the attacks.

Two Chinese nationals and a company will face sanctions, the UK announced on Monday. The British government alleges Wuhan Xiaoruizhi Science and Technology Company Ltd work for the China state-affiliated cyber espionage group Advanced Persistent Threat Group 31 (APT31).

The UK sanctions will freeze assets, barring UK citizens and businesses from handling their funds or resources. A travel ban will also prevent them from entering or remaining in the UK.

Later on Monday, the US said seven Chinese nationals - who allegedly worked for APT31 - had been charged with enacting a widespread cyber-attack campaign. They are accused of ties to a hacking operation that ran for 14 years.

China's Foreign Ministry spokesperson Lin Jian strenuously rejected all the allegations.

"We urge the US and UK to stop politicising cyber security issues. Stop smearing China and stop imposing unilateral sanctions on China. Stop their cyber attack against China," he told a regular press briefing in Beijing on Tuesday.

"The Chinese side has already made technical clarifications and response to the APT 31-related Information submitted by the UK side, which made clear that the evidence provided by the UK was inadequate," he said, adding: "Unfortunately, we haven't heard from the UK side."

Lin Jian also told reporters that China would adopt measures to firmly safeguard its lawful rights and interests.

The cyber attack on the UK Electoral Commission between August 2021 and October 2022 was one of the most significant in British history.

Not only were databases containing names and addresses of people accessed, but also sensitive emails from its "control systems" and between election officials over six by-elections.

But Deputy PM Oliver Dowden told parliament the security of elections had not been compromised and "typically does not create a risk to those affected".

The deputy PM says the UK and international partners will expose China for "ongoing patterns of hostile activity".

Hours later on the other side of the Atlantic, the US state department announced a reward of up to $10m (£8m) for information on the seven men.

The justice department said hackers had targeted US and foreign critics of China, businesses, and politicians.

The seven men allegedly sent more than 10,000 "malicious emails, impacting thousands of victims, across multiple continents", in what the justice department called a "prolific global hacking operation" backed by China's government.

New Zealand's government also said its parliament had been targeted by China-backed hackers, and blamed the Chinese "state-sponsored group" APT40 for the attack.

But New Zealand said it would not introduce sanctions, as it was not part of the government's legislative agenda.