Theresa May today vowed to tear up human rights laws if they 'stop us' from fighting terrorism as she vowed a fresh crackdown on extremism.

The PM also pledged to impose tougher restrictions on would-be jihadis who are known to pose a threat but cannot be prosecuted.

Her plans include doubling maximum detention periods to 28 days, while she also wants universities to do more to flush out potential terrorists.

In a speech in Slough on the eve of the last full day of election campaigning, Mrs May promised to get even tougher with terrorists.

She had earlier admitted there are questions to answer over how the security services handled London bridge killer Khuram Butt - amid anger that at least one of them 'slipped through the net'.

The Prime Minister made clear that the case would be reviewed after it emerged the killer appeared on a TV documentary and was reported to a counter-terror hotline.

She told the rally: 'We need to stamp out extremism in our own communities in Britain.

Theresa May used a campaign speech in Slough to say she will tear up human rights laws if that is what it takes to tackle terrorism in Britain

The Prime Minister made clear that the case would be reviewed after it emerged Khuram Butt, 27, appeared on a TV documentary and was reported to a counter-terror hotline in 2014

'And as we see the threat changing, evolving, becoming more complex, we need to ensure that our police our security and our intelligence agencies have the powers they need.

'And let me just tell you a little bit about what I mean by that.

'I mean longer prison sentences for those convicted of terrorist offences, I mean making it easier for the authorities to deport foreign terrorist suspects back to their own country.

'And I mean doing more to restrict the freedom and movement of terrorist suspects when we have enough evidence to know they are a threat, but not enough evidence to prosecute them in full in court.

'And if our human rights laws stop us from doing it we will change the laws so we can do it.'

In an interview with the Sun, she also said that schools, universities and hospitals should do more to flush out extremists.

Her comments suggest that the Tories will introduce a fresh swath of tough anti-terror legislation if re-elected on Thursday.

Earlier, Mrs May stressed that police and security services had foiled five other potential attacks recently.

And she praised the response of officers on the night who stopped the murderous rampage at London Bridge within minutes by shooting the trio dead.

UKIP COLLAPSE COULD HAND MAY 35 SEATS Huge swathes of Ukip voters defecting to the Conservatives in marginal Labour seats could hand Theresa May a 35-seat boost. In the constituencies in question - many of which in the north of England - Labour either managed to cling onto by their fingertips, or there is a particularly large pool of Ukip voters up for grabs. Seats such as Hartlepool, Birmingham Northfield, Walsall North and Stoke-on-Trent South all had more than 7,000 people vote for Nigel Farage's party in 2015, but a huge dip in poll ratings under new leader Paul Nuttall could leave the door wide open for the Tories. Meanwhile, in the likes of Newcastle-under-Lyme, Wirral West, and Ealing Central and Acton, Jeremy Corbyn will have a majority of less than 100 from the previous election to fall back on, which could present Theresa May with yet more opportunities to make gains. It is predicted that, across the country, more than two million voters will make the switch from Ukip to Conservative and Mrs May's policy of a hard Brexit. Among the Labour MPs who could be under pressure is Helen Goodman, in Bishop Auckland. She has a majority of 3,500 to play with, but is alarmed by the fact that double that number voted for Ukip in 2015. Mrs Goodman told the Sun: 'Make no mistake – contrary to what some claim a clear plurality of 2015 Ukip voters are breaking for Theresa May and the Conservative Party. 'If at least half of them break for the Conservative Party then Labour could have a massive problem on its hands.' Advertisement

Pakistan-born Khuram Butt was given a job on the London Underground (left) despite having appeared in a programme about radical Islamists called 'The Jihadi Next Door'

The emergency services arrived at London Bridge within two minutes of the three killers going on the rampage on Saturday night

'I absolutely recognise people's concerns,' the premier told Sky News. 'We want to stop attacks.'

She went on: 'What we need to do now is see how the threat is evolving… we need to ask how we can adapt our response.'

Mrs May said she was ready to give the security services more powers to help counter the threat.

Earlier, Boris Johnson said the public was right to demand answers about the way the threat was assessed.

But the Foreign Secretary dismissed the idea that cuts to police numbers could be responsible, despite jibes from Labour.

London Mayor Sadiq Khan has attempted to up the pressure on the government two days before the election, claiming that planned budget curbs could mean thousands fewer officers.

Mr Johnson told BBC Breakfast: 'People are understandably right to look at photographs in today's papers of the TV show that this guy was in and to ask what happened, how did this person slip through our net in the way that he seems to have done?

'I can't really comment much about that because there is a live ongoing investigation, but one point I would make for all our viewers is it is very important that we look at this issue, when we look at policing, that we don't take the focus on responsibility away from the people who did it, from the terrorists.'

Jeremy Corbyn bizarrely called for Prime Minister Theresa May to resign yesterday over police cuts. But the Labour leader then backtracked on his demand after he was derided for 'posturing'.

Mr Johnson told the programme: 'When Jeremy Corbyn says it's all a function of police numbers, I have to say first of all I think that is wrong, police numbers in London have remained high.

Earlier today, Boris Johnson said the public was right to demand answers about the way the threat was assessed

'Secondly, we protected police budgets in 2015 and the Labour Party, as I recall, wanted to cut them by 10 per cent.

'All that arguably detracts from the responsibility of these scumbags and what they have done, and we should not allow that to happen.'

Home Secretary Amber Rudd said it was not for her or Mr Johnson to 'say how that happened or what happened'.

She told BBC Radio 4's Woman's Hour: 'It's like any incident - you will look and find out whether there is something to learn.

'I can say with absolute confidence that they will want to do that, but I can say that without, I hope, putting any sort of suggestion of blame because it's very easy to rush in and say 'What went wrong?''

The other two attackers have been named as Youssef Zaghba (left) and Moroccan-born Rachid Redouane (right)

Metropolitan Police Assistant Commissioner Mark Rowley said police and their partners are 'doing everything we can across the country to help prevent further attacks and protect the public from harm'.

He said: 'At any one time MI5 and police are conducting around 500 active investigations, involving 3,000 subjects of interest.

'Additionally, there are around 20,000 individuals who are former subjects of interest, whose risk remains subject to review by MI5 and its partners.'

Security agencies and police have foiled 18 plots since 2013, including five since the Westminster attack.

Butt, who is thought to have also gone by the name Abu Zaitun, was known to neighbours by the nickname 'Abs/z' and was allegedly an associate of radical hate preacher Anjem Choudary.

Transport for London (TfL) confirmed that Butt worked for London Underground for just under six months as a trainee customer services assistant, leaving in October last year.

The father-of-two, who reportedly appeared on Channel 4 documentary The Jihadis Next Door, was also reported to the anti-terror hotline in 2015 for showing signs of 'extremism or radicalisation'.