Two officers were taken to hospital after violence during a second night of disorder in Thetford, where crowds targeted homes they believed were connected to asylum accommodation.
Police in Thetford, Norfolk, have imposed additional public-order measures after two nights of disorder in which crowds targeted residential properties they believed were linked to asylum accommodation and two officers were injured.
The violence has unfolded against a backdrop of intense local opposition to a government proposal to use the former Ministry of Defence site at Barnham, in neighbouring Suffolk, for asylum accommodation.
The plan has not been approved: it remains subject to feasibility work, planning procedures and further government decisions.
The Home Office has said the former military site, if taken forward, would accommodate single adult men seeking asylum and be operated with permanent security and on-site support.
On Wednesday evening, a large group gathered in Thetford after an earlier anti-immigration protest outside the town's police station that officers described as largely peaceful.
At about 9.30pm, police were called to reports that people in the group were trying to enter a residential property.
Officers said members of the crowd became physically aggressive when they intervened.
A male officer was struck with a rock and a female officer was bitten, breaking the skin; both were taken to hospital.
A third officer was spat at.
The incidents followed disorder the previous night, when police were called to reports of a crowd gathering outside several homes.
Windows were smashed, fences were damaged and people attempted to enter one property.
Police also received a report that individuals had forced their way into a home, made a resident leave and stolen a mobile telephone.
The immigration status of the people living at the properties has not been publicly confirmed.
The homes were targeted after assertions circulated locally that they were being used to accommodate asylum seekers.
That claim is central to the protest but is not, by itself, evidence that the occupants were connected to the proposed Barnham site or to the asylum system.
Police moved five men from the area for their safety during the first night of disorder.
The force said its responsibility was to protect everyone in the community, including local residents, people living at the targeted properties and officers on duty.
Two arrests were made following Wednesday's disorder.
Brian Thompson, 68, of Fairfields in Thetford, has been charged with possessing an offensive weapon, described as a wooden bat.
He has been released on bail and is due to appear at Norwich Magistrates' Court on 25 August.
A man in his thirties remained in custody on suspicion of public-order and harassment offences.
A separate man in his thirties, arrested after Tuesday's incidents on suspicion of a public-order offence, was released with a conditional caution.
Norfolk Police have stressed that the right to peaceful protest will be protected, while warning that intimidation, violence and criminal damage will not be tolerated.
The force introduced temporary powers for Thursday evening allowing officers to require the removal of face coverings and to direct people suspected of committing, or likely to commit, antisocial behaviour to leave a designated area.
The Barnham proposal has become a focal point for local concern.
The Home Office is considering the site as part of a wider attempt to reduce the use of hotels for asylum accommodation.
Its current assessment says any future site would begin with smaller numbers before any phased increase in occupancy, while the final capacity has not been confirmed publicly.
The government has said Barnham would be designed to be largely self-sufficient, with accommodation, communal facilities and permanent security on site.
It has also said prospective residents would undergo checks against policing, immigration, security and criminality databases.
The proposal nevertheless has drawn objections from local representatives and residents, who have raised concerns about the scale, pace and local impact of the plan.
Richard Tice, the Reform UK deputy leader and MP for Boston and Skegness, said local people were entitled to express concern about asylum accommodation but that violence had no place.
Terry Jermy, the Labour MP for South West Norfolk, has opposed the Barnham proposal while also condemning vigilantism and attacks on people or property.
The disorder has underlined the distinction between political opposition to government policy and alleged criminal conduct against private residents.
Police are continuing to examine evidence, including footage and witness accounts, while the temporary public-order powers remain in force to prevent further violence.