A Sheffield MP has called for a debate on whether Britain First should be listed as a terrorist group and outlawed in the wake of the Jo Cox murder trial.
Sheffield Heeley MP Louise Haigh has suggested giving the Commons a chance to approve adding the far-right group to the banned list.
The move comes after neo-Nazi Thomas Mair was jailed for the rest of his life yesterday for the shooting and stabbing of the mother of two and MP for Batley and Spen in June.
The 53-year-old shouted the words "Britain first" as he fired three shots at Mrs Cox and stabbed her 15 times, days before the EU referendum.
Speaking in the Commons, Ms Haigh thanked Commons Leader David Lidington for earlier paying tribute to the murdered Labour MP.
She added: "Given those words, can we have a debate about whether Britain First should be proscribed as a terrorist organisation and banned from standing in democratic elections?"
Mr Lidington replied: "I can't offer a debate. As you probably know, the Home Office brings forward orders for the proscription of particular organisations but must do so on the basis of evidence.
"There have been cases in the past where organisations have been so proscribed have gone to the courts and successfully won a judicial review to say that the evidence on which that action had been taken was not sufficient.
"So, I'll make sure that your proposal is reported to the Home Secretary but there has to be clear evidence of terrorist involvement for the terrorist proscription to be applied."
Such proscription orders make it a criminal offence for people to belong to a group, encourage support for it, arrange meetings in support of them or wear clothing or carry articles that arouse suspicion an individual is in favour of them.