China has condemned what it called an "appalling attack" by protesters on Hong Kong's justice secretary in London on Thursday evening.
Teresa Cheng fell and was treated for an arm injury in hospital after being jostled by about 30 supporters of Hong Kong's pro-democracy movement.
Chinese official Geng Shuang said some in the UK "supported violent acts... to create chaos" in its former colony.
Hong Kong has been racked by five months of anti-government protests.
The campaign started in opposition to a now-withdrawn plan to allow extradition to mainland China, but it has since morphed into wider demonstrations backing democracy and opposing the actions of the police.
The protests have continued unabated - Friday was the fifth consecutive day - and have often turned violent. On Thursday, a 70-year-old man died after being hit by a brick thrown during clashes. A murder inquiry has been opened.
Hong Kong meanwhile confirmed it had entered its first recession for a decade, with the economy shrinking 3.2% in July to September, compared with the previous quarter.
What happened to Teresa Cheng?
The justice secretary had been in Camden, north London, to promote Hong Kong as a dispute resolution and deal-making hub.
Video showed her walking towards a lecture at the Chartered Institute of Arbitrators (CIArb) when she was surrounded by a group of protesters.
Some held signs and shouted "murderer" and in the melee, Ms Cheng fell to the ground.
London's Metropolitan Police said they were investigating an allegation of assault and no arrests had yet been made.
"A woman was taken to hospital by London Ambulance Service suffering an injury to her arm," a statement said.
In a statement, CIArb said Ms Cheng had been "assaulted by a crowd".
But one of the protesters told the Guardian she had slipped trying to escape from the crowd and "nobody laid a hand on her".
Tom Tugendhat, chair of parliament's foreign affairs committee, condemned the behaviour of the protesters.
Ministers "visiting the UK should be able to go about their business free from abuse and assault. This is not right", he tweeted.
How did China react?
Mr Geng, China's foreign ministry spokesman, said the attack was "directly related to certain British politicians confusing right from wrong on the Hong Kong issue and their support for violent acts, giving a platform to those who are anti-China and want to create chaos in Hong Kong".
He said if the UK did not alter its approach "and continues to add fuel to the fire, sow discord and instigate others" it would "bring calamity on itself".
He urged the UK to "bring the culprits to justice and... also protect the safety and integrity of all Chinese people in the nation".
Hong Kong Chief Executive Carrie Lam also condemned the protesters in the UK, saying "the savage act breached the bottom line of any civilised society".
Ms Cheng's office said she "castigates the violent mob in London causing her serious bodily harm on her way to an event venue".
Protesters say Ms Cheng played a key role in pushing for the extradition bill.
What's the latest on the protests?
Protesters, including thousands of office workers, were on the streets again on Friday, many of them chanting "stand with Hong Kong".
A number of roads were blocked and there was more disruption on the underground rail system. Black-clad protesters also continued to occupy university campuses.
It comes a day after Chinese President Xi Jinping warned the protests were threatening the "one country, two systems" policy under which Hong Kong retains a high level of autonomy and personal freedom unseen in mainland China.
Police in Hong Kong are treating as murder the death of the 70-year-old hit by a brick during unrest in the border town of Sheung Shui on Wednesday.
The government said the cleaner was on a lunch break when he was struck by "hard objects hurled by masked rioters".
Video purported to be of the incident shows two groups throwing bricks at each other before the man falls to the ground.
On Monday, a police officer shot an activist in the torso with a live bullet, and a man was set on fire while arguing with anti-government protesters.
A week ago, Alex Chow, a 22-year-old student, died after falling from a building during a police operation.