Theresa May has said she will change human rights laws if they "get in the way" of tackling suspected terrorists.
The PM said she would make it easier to deport foreign terror suspects and "restrict the freedom and movements" of those that present a threat.
Labour said it was "not the message that we should be sending".
Security has dominated the final days of the general election campaign after the terror attacks in London and Manchester.
Rival parties have been criticising the Tories over police cuts.
Speaking after the London attack, Mrs May said "enough is enough" and that "things need to change" in the terror fight.
Addressing activists in Slough on Tuesday evening, she did not make any specific new policy proposals but said: "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 countries.
"And I mean doing more to restrict the freedom and 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.
"And if our human rights laws get in the way of doing it, we will change the law so we can do it."
In an interview with The Sun, Mrs May said she would also consider extending the time suspects can be held without charge to 28 days, after it was reduced to 14 days in 2011 under the coalition.
"We said there may be circumstances where it is necessary to do this.
"I will listen to what they [the police and security services] think is necessary for us to do," she said.
More:
http://www.bbc.co.uk/news/election-2017-40181444
