Speaking in the wake of a terrorist attack in London that left seven dead
, May said she would seek to introduce longer prison terms for those convicted of terrorist offenses and make it easier to "deport foreign terrorist suspects."
The UK goes to the polls Thursday to decide if May's Conservative government stays in power.
Security has become a major issue since the London attack, and May has faced intense criticism in recent days
from opposition Labour leader Jeremy Corbyn over her record as Home Secretary, during which she oversaw cuts to police officer numbers by over 20,000.
Seeking to shore up her domestic security credentials, May said Tuesday more should be done "to restrict the freedom and movement of terrorist suspects when we have enough evidence to know they are a threat but not evidence to prosecute them in full in court, and if our human rights laws stop us from doing it, we'll change the laws so we can do it."
May has previously called for closer regulation of the internet to tackle extremism
, and criticized social media firms for not doing enough to police their platforms.
British security services already possess wide anti-terrorism powers that have been denounced
by Amnesty International as among "the most draconian" in Europe.
Khuram Butt, the alleged ringleader of the London attack, was well known to police and intensely investigated
, raising questions over whether enough was done to prevent it.
Another of the three attackers, Youssef Zaghba, was also on a terrorist watch list after he was stopped in Italy headed to Syria with extremist materials
UK Foreign Secretary Boris Johnson said earlier this week that British intelligence agencies had questions to answer, adding that people would be asking "How on Earth could we have let this guy or possibly more through the net?"
Butt, Zaghba and another man, Rachid Redouane, rammed a van into pedestrians on London Bridge before launching a stabbing spree in bars and restaurants at nearby Borough Market on Saturday night. At least seven people were killed and dozens were injured. The three terrorists were shot dead by police.
A 30-year old man was arrested in east London early Wednesday, police said. Twelve others arrested after the attack have since been released without charge.
Speaking Tuesday, May said more needed to be done "to restrict the freedom and movement of terrorism suspects when we have enough evidence to know they are a threat but not enough evidence to prosecute them in full in court."
As Home Secretary, she oversaw the replacement of control orders -- sweeping powers introduced in 2005
that placed extreme limits on the freedom and movement of terrorism suspects -- and their replacement with what some critics have described as "watered down
While control orders were widely criticized by many judges and human rights campaigners, the UK's top court ruled on several occasions
that onerous restrictions on the freedom of unconvicted suspects was nevertheless in accordance with the European Convention on Human Rights
In the past, May has called for the UK to withdraw from the ECHR
and replace its human rights protections with a British "bill of rights."
While European Union countries are all signatories to the convention, Brexit does not mean the UK will automatically or necessarily withdraw from it.
The Conservative Party election manifesto
calls for the UK to remain a signatory "for the duration of the next parliament."
Speaking Tuesday, however, May echoed many of her previous criticisms of the ECHR -- though she did not mention it by name -- saying it needed to be easier to kick terror suspects out of the UK.
The European Court of Human Rights -- which upholds the convention -- has ruled that people cannot be deported to another country if they face the risk of torture or execution there.
In a statement
, UK campaign group Liberty accused May of wanting to rip up British human rights laws.
"If Theresa May does what she threatens, she will go down in history as the Prime Minister who handed terrorists their greatest victory," said the group's director Martha Spurrier.
"For cheap political points and headlines, she is willing to undermine our democracy, our freedom and our rights -- the very things these violent murderers seek to attack."