Sir Mark Rowley’s proposals for a new law banning hateful extremism are unlikely to work, the Government’s adviser on terrorism legislation has said.

Jonathan Hall KC suggested instead that ministers should consider a specific new offence to close the gap in the law which the Metropolitan Police Commissioner has blamed for hampering his officers’ ability to tackle extremism at pro-Palestinian protests.

In an article for the Telegraph on Tuesday, Sir Mark argued there was a “chasm” between the law and what the public expected as he warned that extremists could steer around it to propagate “some pretty toxic messages” in the wake of the Hamas terrorist attack on Israel.

The spotlight has focused on the Metropolitan Police after protesters at Saturday’s march in London were filmed shouting “Jihad, jihad, jihad.”

After analysing an online video, the Met said that “jihad” had “a number of meanings” and concluded that no offence had taken place.