Labour MP Jess Phillips said a man has been arrested after banging on the windows of her constituency office and shouting "fascist".
The Birmingham Yardley MP had spoken out in the House of Commons on Thursday over language used by Boris Johnson on parliament's resumption following its unlawful proroguement.
The prime minister came under fire for calling a law aimed at blocking a no-deal Brexit the "surrender bill", and for claiming that murdered MP Jo Cox would have wanted to get "Brexit done".
Ms Phillips claimed an arrest had been made in connection with the alleged incident on Thursday. She has been in London throughout the day to speak in parliament.
She told ITV News Political Correspondent Dan Hewitt that staff at her office had to lock themselves into the building as the man allegedly tried to break in.
West Midlands Police: "Police were called to reports of a disturbance outside an address on Yardley Road in Acocks Green, Birmingham just before 2.25pm this afternoon (26 September).
"A 36-year-old man has been arrested on suspicion of a public order offence and possession of cannabis. He’s been taken into police custody and will be questioned in due course."