Theresa May has said she is prepared to throw out human rights laws if they restrict new tougher legislation to tackle terrorism.
The Prime Minister said she will make it easier to deport foreign terror suspects back "to their own countries" and would "restrict the freedom and movements of terrorist suspects" if re-elected on 8 June.
Addressing supporters in Slough just 36 hours before the polls open, she vowed to change the laws if they impeded efforts to fight the increasingly "complex" terror threat.
"As we see the threat changing, evolving becoming a more complex threat, we need to make sure that our police and security and intelligence agencies have the powers they need," Ms May said.
"I mean longer prison sentences for people convicted of terrorist offences. I mean making it easier for the authorities to deport foreign terrorist suspects back to their own countries."
She continued: "And I mean doing more to restrict the freedom and the movements 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.
It also emerged the third attacker to be named, Youssef Zaghba, had been reported to UK and Moroccan authorities by Italian intelligence agencies after he attempted to fly to Turkey and travel on to Syria last year.
"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 told Sky News.
"What 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 United Kingdom."