Pro-Brexit protesters who yelled abuse at the Conservative MP Anna Soubry outside Parliament have been condemned as "appalling" by Carlisle MP John Stevenson.

More than 50 MPs have written to the Metropolitan Police commissioner Cressida Dick urging her to improve the protection for politicians amid mounting concerns about the increasingly aggressive tone of UK political debate. TV footage of Miss Soubry being harassed by the activists has shocked many people.

As she was being interviewed by a TV journalist outside Parliament, a group of protesters yelled abuse at her, calling her a Nazi.

Then as she arrived at the entrance to the Palace of Westminster, the group repeatedly yell the word "scum" at her.

"It was appalling behaviour," said Mr Stevenson.

"It doesn't matter what side of the argument you are on, that kind of behaviour shouldn't be tolerated. This country has a long tradition of having vigorous political debates, which is conducted in a mature and respectful way.

"People can have very strong views, and differences of opinion but even at a local level I'm starting to see a more aggressive tone - an unnecessarily aggressive tone. People may have different interpretations of Brexit but that doesn't given anybody the right to behave in that aggressive way.

"A majority of people in this country voted to leave EU institutions, and most politicians - including myself - fully accept that; but our future relationship with the EU was not decided by the referendum there are quite legitimate arguments to be had about what that future relationship should be."

More than 50 parliamentarians have now signed the letter to Cressida Dick after Commons Speaker John Bercow urged officers to do more to protect MPs.

Anna Soubry also criticised the lack of police response to the abuse.

Scotland Yard has confirmed it is now investigating whether any offences were committed as the former minister was yelled outside Parliament on College Green.

It is the second time in recent weeks that Soubry has been targeted by pro-Brexit protesters - including some who yelled that she was a traitor.

In their letter to the police commissioner, the MPs say: “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.

“We understand there are ongoing investigations but there appears to be an ongoing lack of coordination in the response from the police and appropriate authorities including with Westminster borough policing, and despite clear assurances this would be dealt with following incidents before Christmas, there have been a number of further serious and well publicised incidents today.

"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.”