More than 50 MPs have written to the Metropolitan Police Commissioner to express their “serious concerns” about the “deteriorating public order and security situation” outside Parliament.
The letter comes as police investigate whether any criminal offence was committed when Tory MP Anna Soubry was branded a “Nazi” by protesters during live TV interviews on College Green on Monday.
A cross-party group of at least 55 MPs signed the formal letter to Cressida Dick criticising a “lack of co-ordination” in the response from the police and appropriate authorities despite assurances that incidents before Christmas would be dealt with.
The MPs said: “We write to express our serious concerns about the deteriorating public order and security situation in and around the exterior of the parliamentary estate including College Green.
“After months of peaceful and calm protests by groups representing a range of political views on Brexit, an ugly element of individuals with strong far right and extreme right connections – which your officers are well aware of – have increasingly engaged in intimidatory and potentially criminal acts targeting Members of Parliament, journalists, activists and members of the public.”
The attack on Ms Soubry was widely condemned on Monday, with Commons Speaker John Bercow saying he was “concerned” about a “pattern of protest” targeting female MPs and journalists.
The letter to Ms Dick, co-ordinated by Labour MP Stephen Doughty, added: “The ability to peacefully protest and express views outside Parliament is a cherished part of our democracy – and we want to retain the right for those who have conducted themselves within the law and a peaceful way to continue to do so.
“It is however utterly unacceptable for Members of Parliament, journalists, activists and members of the public to be subject to abuse, intimidation and threatening behaviour and indeed potentially serious offences while they go about their work.”
MPs said they had repeatedly raised concerns with police on the ground and at senior level as the “situation worsened”.
Ms Soubry told BBC interviewer Simon McCoy: “I do object to being called a Nazi, actually.
“I just think this is astonishing, this is what has happened to our country. But let’s try and move on and be positive about things.”
Protesters also chanted slogans including “Liar, liar” throughout a live interview with Ms Soubry on Sky News.
A spokesman for the Metropolitan Police said: “Police received a third-party report of a public order offence on Monday 7 January, in the area of College Green, SW1.
“Officers are assessing if any crimes have been committed. There has been no arrest at this stage.”
Ms Soubry, the pro-EU MP for Broxtowe, said the behaviour of protesters was “seriously worrying”, adding: “I’m afraid the truth is that Brexit has unleashed these people. This is Britain now.
“This is not the country I know and love and these people do not represent our country and they need sorting out.”
The protesters were also criticised by high-profile Brexit supporters, including presenter Piers Morgan and former MP Douglas Carswell.
Earlier on Monday, political commentator Owen Jones shared a video on Twitter which showed him being accosted by a group outside Parliament, including men wearing Union flags.
They could be heard calling him a “traitor” and a “horrible little man” and accusing the Labour activist of writing “fake news”.
Mr Doughty raised the issue in the Commons during a Brexit question session and called on Mr Bercow to intervene.
The Speaker said he was “keeping a close eye on events” as he voiced concerns over incidents involving “aggressive and threatening behaviour” towards MPs.
Theresa May’s official spokesman said he had not discussed the incident involving Ms Soubry with the Prime Minister, but added: “The Prime Minister has been very clear that nobody involved in the political process should be subjected to abuse or harassment.
“They should be free to do their job without any form of intimidation and it is clearly unacceptable when that isn’t the case.”
Asked whether MPs should be offered greater protection while the “meaningful vote” on Brexit is debated over the next few days, the PM’s spokesman said: “There are existing laws in relation to public order, harassment and making threats.
“Where laws are already in place, it’s important that they are respected.”