The UK’s anti-radicalisation scheme Prevent needs to be strengthened to confront extremists after the infiltration of the programme by “highly questionable groups”, a former counter-terrorism police chief has warned. In a five-part manifesto after the fatal stabbing of British MP David Amess last week, Sir Mark Rowley said the programme needed reforming to confront violent ideologies. A man arrested over Amess’s killing, Ali Harbi Ali, was reportedly referred to the voluntary scheme seven years ago and was on the government’s deradicalisation and mentoring scheme known as Channel. Prevent is currently under review after complaints from Muslim communities that they have been unfairly targeted and a series of terrorist attacks involving extremists who were on deradicalisation programmes. “The Prevent programme needs reform to become more expert, assertive, and prepared to confront violent ideologies,” wrote Mr Rowley, the head of UK counter-terrorism policing for four years, in an article for <i>The Telegraph</i> newspaper. “This is especially true with Islamist extremists, where naive cultural sensitivity and, in some cases, infiltration of Prevent by highly questionable groups, creates undue caution in some areas. Islamist extremists have no sympathy from the vast majority of Muslims.” He said he had lost count of the number of times that senior police from Muslim countries had told him of their “bewilderment” at what terrorist-sympathising ideologues were able to get away with in Britain. “In particular, they are shocked at the hateful rhetoric and glorification of terrorist violence we allow to undermine us,” he said. Mr Rowley called for a change in the law to outlaw the glorification of terrorism. He has previously warned of a gaping chasm in the law that allows extremists to evade prosecution. In a report this year, he said weak anti-terrorism laws meant it was legal to “hero worship” the terrorists behind the attacks on New York and Washington on September 11, 2001. He said that tougher sentences were needed for extremists and more work was required to mend the divisions in British society that violent extremists are able to exploit. He called for changes to crack down on the spread of extremist ideologies online, which he said government lawyers had considered to be too difficult. “This sense of an anonymous ‘wild west’ needs to be broken, by forcing social media companies to change their operating model,” he wrote. He said such businesses should invest in specialists to provide “virtual minders” for MPs who have been inundated with hate mail and death threats. Another attack on an MP after the killing of Amess is now considered likely after intelligence officers upgraded the threat level for politicians to "substantial". Home Secretary Priti Patel on Wednesday urged parliamentarians to take the change in risk seriously but said there was no "specific or imminent threat". The killing of Amess at a constituency meeting last week in Leigh-on-Sea, Essex, was the second of an MP in five years. Opposition Labour MP Jo Cox was murdered in her constituency in 2016 by a right-wing extremist.