A protester dragged into the Chinese consulate in Manchester and punched has spoken out about his "unprovoked" ordeal.
Bob Chan who was protesting outside a Chinese consulate in the north-west city said he was physically taken inside the grounds by masked men kicked and punched in an attack.
Foreign Secretary James Cleverly described his treatment on Wednesday as "unacceptable".
China has disputed the account of events which took place during a demonstration on Sunday against Chinese President Xi Jinping outside the consulate in Manchester, insisting protesters had stormed its grounds.
It is the latest diplomatic spat between Britain and China, whose relationship has soured in recent years.
Footage on social media showed a man, wearing a black cap and with a ponytail, being hauled through a gate into the consular grounds, where he was assaulted by five men as he lay on the ground.
Bob Chan, who is aged in his 30s and originally from Hong Kong, said the attack started when masked men came out of the consulate to take away banners from peaceful protesters.
He said: "I then found myself being dragged into the grounds of the consulate. I held on to the gate where I was kicked and punched.
"I could not hold on for long and was eventually pulled into the grounds of the consulate."
He said the attack only stopped when a police officer moved in to free him.
Mr Chan claimed he was left with bruising to his eye, head, neck and all over his back
He said: "I am shocked and hurt by this unprovoked attack."
He was also concerned about his and his family's safety.
Britain summoned China's Charge d'Affaires in London yesterday to explain what had happened.
Mr Cleverly said the protest, which involved 30 to 40 people, including Hong Kong citizens now resident in Britain, had been peaceful and legal.
He said "They were on British soil and it is absolutely unacceptable for this kind of behaviour"
China said it had lodged representations with Britain "about the malicious harassment incident".
Zheng Xiyuan, the Chinese Consul-General, wrote to police to say he was disappointed with how they handled the protest.
It included images of Xi with a noose around his neck and slogans written in Chinese reading "God Kill CPC" (Communist Party of China).
"At one point the consulate grounds were stormed by a group of protesters and members of consular staff were required to fend off unauthorised entry and subsequent assaults," he wrote in a letter released to media.
He said that a protester had grabbed a member of staff during a scuffle and refused to let go.
Colleagues he said had pulled them inside and the attacker "continued assaulting our staff
member and so our staff were forced to disentangle his hands".
The protest took place at the start of a twice-a-decade congress of China's ruling Communist Party in Beijing as Xi is widely expected to win a third leadership term.
Police said they were investigating and appealed for more videos of the incident, saying there had been no arrests yet.
Cleverly said Britain would decide "what more we might need to do" once the police conclude their inquiry.
Some lawmakers said the diplomats involved should be immediately expelled.
Iain Duncan Smith, a former leader of the governing Conservative Party, said video footage showed that the Consul-General's claims were "complete nonsense".
Duncan Smith was among the lawmakers and other Britons sanctioned by China last year for spreading "lies" about alleged human rights abuses in Xinjiang.
Relations between Britain and China have been increasingly tense since Beijing brought in a national security law in Hong Kong, which returned to Chinese rule in 1997.
Britain has been critical of the law, which it says has been used to suppress dissent, Beijing, meanwhile has accused London of interfering and creating trouble.
A programme allowing almost three million people in Hong Kong to apply for visas in Britain has been part of the contention.