LONDON — Anger mounted in Britain yesterday over how one of the London attackers slipped through police surveillance, as Prime Minister Theresa May came under pressure two days before an election.

The British government’s confirmation that one of the three assailants in the weekend’s deadly attack was yet again someone that had been known to police has put more pressure on security agencies seen as notdoing enough to deal with the terror threat.

Officials confirmed that Khuram Butt had been investigated in 2015, but his case was ranked in the “lower echelons” of counter-terrorism investigations and he was not suspected of planning an attack.

Questions are now being raised about why the police and the MI5 security service failed to prevent three attacks in three months, and why Butt was not monitored more closely, given his links to al-Muhajiroun, the banned extremist group whose leader, Anjem Choudary, has been linked to the recruitment of more than 100 British terror suspects.

The attackers in two previous incidents had also been known to the authorities, putting further pressure on Mrs May who has faced criticism over her move to cut the number of police officers by 20,000 between 2010 and last year when she was interior minister. Security has become a key issue in tomorrow’s general election.

Former counter-terrorism chief Robert Quick yesterday said cuts to police funding have affected efforts to prevent attacks, including a lack of intelligence from the ground on people voicing support for terrorism. “Counter-terrorism funding is ringfenced but cuts to the general policing budget have impacted on neighbourhood policing teams in many parts of the country including London,” The Guardian quoted him as saying.

“This has reduced the capacity of the police to work in communities building relationships and trust to in turn generate community-based intelligence about persons of concern.”

In response to the criticism, Mrs May said yesterday she expects the police and security services to embark on a review of their operations.

“MI5 and the police have already said they would be reviewing how they dealt with Manchester and I would expect them to do exactly the same in relation to London Bridge,” she said.

“What the government needs to do is, and what the government that comes in after Thursday’s election needs to be willing to do, is to give more powers to the police and security service when they need them, needs to deal with this issue of terrorism and extremism online and also needs to be able to call out extremism here in the UK.”

Her remarks came following a poll published earlier yesterday by the group Survation which showed Mrs May’s lead over the opposition Labour has shrivelled to just over a single point — 41.6 per cent to 40.4 per cent.

Opposition leader Jeremy Corbyn had called for Mrs May to resign and pledged to hire thousands of officers for neighbourhood duties, arguing that a grassroots approach would curb crime and radicalisation.

As the debate rages over security, the British police yesterday named the third person in the weekend attack as Youssef Zaghba, 22, believed to be an Italian national of Moroccan descent.

The police had named the other two attackers as Butt and Rachid Redouane. Both Zaghba and Redouane were not on the authorities list.

The trio rammed a van into pedestrians on London Bridge on Saturday evening before running into the bustling Borough Market area, where they slit throats and stabbed people. All three attackers were shot dead at the scene by officers.

“Why didn’t they stop TV jihadi?” The Sun asked on its front page, while The Daily Mirror asked: “So how the hell did he slip through?”

The conservative Daily Telegraph added: “It is astonishing that people who pose such a danger to life and limb should be able to parade their foul ideology on TV with no consequences.”

The MI5 has 4,000 officials to keep tabs on 3,000 people classified as “subjects of interest” although counter-terrorism accounts amounted to over 60 per cent of what it does.

Of the 3,000 people, only “a tiny proportion” are placed under 24-hour surveillance if they are suspected of planning an attack. Each of such surveillance typically requires two dozen or more officers, which limits the number of targets that can be closely monitored.

Still, London mayor Sadiq Khan urged the police and MI5 to respond to questions about why they knew about Butt but did not act on warnings about his behaviour.

“Not unreasonably, these questions are being asked,” he told the BBC.

He also called on the government to cancel United States President Donald Trump’s state visit to Britain after the mercurial leader criticised the British Muslim mayor in two tweets, which misconstrued a statement from Mr Khan.

“I don’t think we should roll out the red carpet to the President of the USA in the circumstances where his policies go against everything we stand for,” Mr Khan said.

“When you have a special relationship it is no different from when you have got a close mate. You stand with them in times of adversity, but you call them out when they are wrong. And there are many things about which Donald Trump is wrong.” AGENCIES