Speaker John Bercow has described the abuse and harassment of MPs outside Parliament as "a type of fascism" and called for a change of policing policy. He said recent incidents, including Tory MP Anna Soubry being verbally abused on Monday, were "intolerable".
At least 115 MPs have called on police to improve their response to abusive protesters outside Parliament. The Metropolitan Police has said it is ready to "deal robustly" with any instances of criminal harassment.
Deputy Assistant Commissioner Laurence Taylor said the force was assessing whether any crimes had been committed, following a third-party report of a public order offence on College Green, opposite the Houses of Parliament.
He said Scotland Yard will be "enhancing the policing presence" in the run-up to next week's vote on Theresa May's Brexit deal. Revised advice was issued to MPs by Parliament security on Tuesday. Meanwhile, a man has been arrested on suspicion of trespassing after he tried to get into Parliament.
Armed officers arrested him at about 19:20 GMT on Tuesday after he got through Carriage Gates, at the entrance to the Houses of Parliament. He was taken to a police station, the Metropolitan Police said. The incident is not being treated as terror-related.