The foreign secretary, James Cleverly, has not ruled out Chinese officials being prosecuted or expelled from Britain for the “completely unacceptable” violence against pro-democracy protesters in Manchester.

Cleverly said he had summoned China’s chargé d’affairs in London “at the first available opportunity” to demand an explanation over the incident outside the Chinese consulate on Sunday.

A pro-democracy Hong Kong protester, named only as Bob, needed overnight hospital treatment after being beaten by men who appeared to emerge from the consulate to confront campaigners over “offensive” banners.

One of China’s most senior diplomats in the UK, Zheng Xiyuan, claimed his staff were attacked by a mob who had “stormed” Beijing’s Manchester headquarters.

Footage posted online showed a person, believed to be Zheng, the consul general, kicking down banners and forcefully grabbing Bob’s hair before the protester was pulled inside the consulate grounds and beaten.

On Tuesday, Beijing’s foreign ministry spokesperson declined to confirm or deny whether Zheng had been involved in the incident, Reuters reported.

The UK government has been urged to prosecute or expel any Chinese officials found by Greater Manchester police (GMP) to have attacked campaigners.

Speaking on BBC Radio 4’s Today programme on Wednesday, Cleverly said: “Greater Manchester police are conducting an investigation. Once I get the details from that I’ll see what other action I might choose to take in response to that.

“But I made it very clear at the first opportunity that this is completely unacceptable behaviour. The right thing now to do is to get the full facts from the police investigation.”

Asked whether there was a possibility that some officials not covered by diplomatic immunity could be prosecuted, he added: “I don’t want to speculate about what we might do in response to the information we get from the Greater Manchester police.”

The Chinese consulate released a letter it has provided to GMP in which it claims that the building was “stormed” by a mob of protesters who had displayed “deeply offensive imagery and slogans”.

Footage filmed by campaigners appeared to show several men, including one wearing a riot helmet and two wearing stab vests, emerge from the consulate and start tearing down banners before the violence erupted.

Read Related Also: Meet Taylor Forrest Wife Jimmy Diresta: Net Worth 2022

Several of these men were filmed punching and kicking the protester named Bob after dragging him inside the grounds of the consulate, where UK police need permission to enter.

A police officer could then be seen pulling Bob away from the assailants, the footage showed.

In a statement on Monday, GMP said: “Shortly before 4pm a small group of men came out of the building and a man was dragged into the consulate grounds and assaulted. Due to our fears for the safety of the man, officers intervened and removed the victim from the consulate grounds.

“The man – aged in his 30s – suffered several physical injuries and remained in hospital overnight for treatment. He is continuing to receive our support for his welfare.”

Earlier on Tuesday, China’s foreign ministry challenged the British police account of an assault by claiming the man had entered the compound illegally.

In a letter to police, given to the Manchester Evening News, the consul general said the protester had “plunged” into the property after grabbing a member of consular staff by the neck.

Zheng said the activists had displayed slogans that were “deliberately designed to provoke, harass, alarm and distress our consular staff” and as a result were contrary to the Public Order Act. He said they were “asked politely” to remove the imagery “but refused to do so”.

He added in the letter: “At one point the consulate grounds were stormed by a group of protesters and members of consular staff were required to physically fend off unauthorised entry and subsequent assaults.

“During the ensuing scuffle, one of the protesters grabbed a member of consular staff by the neck and refused to let go. In an effort to free the staff member, other members of staff pulled their colleague into our compound. Despite this, the attacker persistently refused to let go and plunged into the property himself.”

It is understood that some of the alleged assailants have been identified by the police and are likely to have diplomatic immunity, which means they cannot be arrested or prosecuted by UK authorities.

GMP’s major incident team is investigating and will share its findings with Foreign Office officials in London. The FCDO will then have to decide whether to take the extraordinary step of expelling any Chinese diplomats found to be involved, in what would mark a serious escalation of tensions with Beijing.