Dozens of 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.

As tensions in Westminster heightened before a vote on the Prime Minister's Brexit deal next week, a business minister vowed to resign from the Government if it proved necessary to stop no deal.

READ MORE: Video: Fury as MP Anna Soubry receives Nazi taunts outside Parliament 

Meanwhile, amendments will be submitted to the Budget-enacting Finance Bill which returns to the Commons on Tuesday in an attempt to block a no-deal Brexit.
The amendment tabled by Labour former cabinet minister Yvette Cooper and Conservative ex-education secretary Nicky Morgan would restrict the Government's freedom to make Brexit-related tax changes without parliamentary safeguards.

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 incidents before Christmas would be dealt with.

MPs wrote: "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."

Business minister Richard Harrington said he would definitely quit to prevent the UK crashing out of the EU without a deal, but said he believed Britain would leave with the Prime Minister's deal.

"We will not be leaving with no deal," he told BBC Two's Newsnight. "We're going to leave with the Prime Minister's deal. And I think people are beginning to realise that it's the Prime Minister's deal or there may not be a Brexit."

But asked whether he was prepared to resign to stop a no deal Brexit, Mr Harrington said: "Definitely, I would."

And there was no sign of a breakthrough among MPs who have vowed to vote against Theresa May's deal as they left Downing Street following a drinks reception for Tory MPs.

Conservative former Cabinet minister and Brexiteer Theresa Villiers said the evening "hasn't changed my view" and that she would still not be supporting the agreement.
DUP Westminster leader Nigel Dodds described the meeting as a "very pleasant social occasion".

But asked whether words of comfort from the EU would be enough to change his party's stance on the deal, he told reporters: "Let us wait and see what comes forth in the course of the next few days but there hasn't been much so far, so we'll see what happens in the next little while."

Another reception will be held on Wednesday as part of the Prime Minister's charm offensive.

And more than 200 MPs who signed a letter to the PM urging her to rule out a no-deal Brexit have been invited to meet Mrs May at Downing Street on Tuesday.

On Monday, Brussels said the agreed Brexit deal was "the best and the only deal possible" and the Commission was focused on watching what happened in the vote.

Without some activity from Brussels Mrs May is expected to lose the so-called meaningful vote on January 15, which was postponed in December when it became clear the Government would be defeated.