Theresa May issued an appeal to voters regarding Labour
Mrs May said: "It's about which leader and which team people trust to take the big decisions that matter to Britain, about which leader and which team people trust to keep Britain safe."
Her remarks came as the election battle resumed after a brief campaign pause following the massacre by knife-wielding terrorists at London Bridge at the weekend.
Keeping our country safe should be the number one priority for any Prime Minister and any government
Security soared to the top of the election agenda after Mr Corbyn called for the Prime Minister to resign in the wake of the surge in terrorist violence.
In a near-hysterical intervention, the Labour leader claimed Mrs May should stand down just three days before the election because she had "presided over these cuts in the numbers" of police during her time at the Home Office.
But Mrs May dismissed Mr Corbyn's calls for her resignation.
And she sought to contrast her record on security with the Labour leader's decades of peacenik posturing, backing for nuclear disarmament and links with extremist groups.
Mrs May said in a speech at the Royal United Services Institute, a military think tank based in Whitehall a short walk from the Ministry of Defence: "Keeping our country safe should be the number one priority for any Prime Minister and any government.
Theresa May insisted the general election had come down to choice about leadership
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"Yet in this election there is one leader who has made it his life's ambition to get rid of Trident, and one who is committed to keeping it; one leader who has boasted about opposing every single counter-terror law, and one who has been responsible for passing them; one leader who has opposed the use of shoot to kill, and given cover to the IRA when they bombed and shot our citizens – and who now, in the midst of an election campaign, wants to do all he can to hide or deny those views.
"That's not leadership – it's an abdication of leadership."
Mrs May warned that the Labour leader's track record showed that he failed "to meet even the minimum requirement of the job of Prime Minister – to keep our country safe".
Defending her record on backing the police and security services during her time at the Home Office and in Downing Street, the Prime Minister said: "Safeguarding the security of our country takes leadership.
"That is why since 2010 in the face of a growing threat, we have protected the budget for counter-terrorism policing – and increased the resources available to the security and intelligence agencies.
"It is why since 2015 – when Jeremy Corbyn's front bench was arguing for the police to be cut by a further ten per cent – we have not cut the police but protected their budget."
She pointed out that the Government under the Tories had increased the number of armed police officers, improved cooperation between the police and specialist military units, and provided funding for an additional 1,900 officers at MI5, MI6 and the security monitoring service at GCHQ.
Mrs May accepted the government "must do more" to respond to the changing terrorist threat.
She said: "We cannot deny that the threat from Islamist Extremism is one of the gravest we face.
"I believe it is right that the UK is engaged in taking on and defeating groups like ISIS and their like around the world. It is in our own national interest to do so, and it is in the interests of the wider world.
"But as our efforts to defeat them overseas are ever more successful, they are increasingly seeking to spread their poisonous ideology and to prey on the weak and vulnerable in our own countries, inspiring them to commit acts of terror here at home."
Mrs May vowed to step up her fight against terrorist propaganda on the internet and the spread of Islamist extremism throughout British society.
She said: "We cannot go on as we are. Enough is enough."
"We must do more – much more – to take on and defeat the evil ideology of Islamist extremism that preaches hatred, sows division, and promotes sectarianism.
"It is an ideology that promotes a false choice between our Western values of freedom, democracy and human rights and the religion of Islam.
"It is a perversion of Islam and a perversion of the truth. "And it will only be defeated when people understand that our values – pluralistic, British values – are superior to anything offered by the preachers and supporters of hate.
Mrs May said Mr Corbyn's track record showed failure to meet minimum requirement of being PM
"We must deny it the safe spaces it needs to take root and grow."
The Prime Minister added: "We will do more to deny this ideology the physical space to breed here at home. "That means refusing to tolerate extremism of any kind in our country.
"It means being more robust in identifying it and stamping it out – across the public sector and across wider society."
Britain was facing huge challenges over security, the economy and the Brexit negotiations, the Prime Minister said.
Mrs May said: "We need that strong leadership now more than ever.
"The question of leadership has always been at the heart of this campaign – and it is absolutely crucial we get the answer right.
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"The ability to say the courageous thing and do the difficult thing; to face up to and address great challenges, not to pretend they don't exist or seek to wish them away; the strength to be straight with people and not just tell them what they want to hear; the ability to get the job done – that is what leadership means to me."
Mrs May spoke of her sorrow and revulsion at the recent terror attacks.
She said: "When this campaign started, we could never have predicted the tragic turn that events would take.
"We could never have imagined the appalling depravity that led a cowardly and callous killer to target innocent men, women and children in the way that we saw in Manchester two weeks ago, nor could we have envisaged the brutal attack that was carried out on the streets of London on Saturday evening."
And in a highly personal appeal to voters, she admitted she spoke of how she wanted to get on with the job of leadership in her own understated way.
She said: "A year ago, I launched my campaign for the leadership of the Conservative Party in this very room.
Mrs May said it was "abdication of leadership"
"I said at the time that I'm not a showy politician, I don't tour the television studios, I don't gossip about people over lunch, I don't go drinking in Parliament's bars, I don't often wear my heart on my sleeve and that's true.
"But I said then – and I say now – that if ever there was a time for a Prime Minister who is ready and able to do the job from day one, this is it because there's no time for learning on the job.
"The demands of the role are significant, the ability to master the details crucial, and the need to make big, important decisions, inescapable."
Mrs May also warned that whoever is Prime Minister after the votes are counted on Friday will have to be ready for the talks with Brussels on exiting the EU.
She said: "With the Brexit negotiations beginning just 11 days' after polling day, we have no time to waste.
"So I offer myself as Prime Minister once more, with a resolute determination to get on with the job of delivering Brexit, confidence that I can get a deal that works for all, and belief that I have the vision, the plan, the will and the experience to fulfil the promise of Brexit and build a better Britain."
She added: "We do know something that Jeremy Corbyn says he would do on day one; he would throw away our negotiating position at a stroke by rejecting the very idea of walking away with no deal.
"Now, I often say 'no deal is better than a bad deal' because that is in Britain's national interest. "Jeremy Corbyn seems to think that any deal – no matter what the price, no matter what the terms – is better than no deal.
"That's not leadership. That's an abdication of leadership. "The bureaucrats in Brussels would think Christmas had come early if the British government adopted such an approach.
"Yet that is exactly what Jeremy Corbyn is proposing, and that is why he is not fit to negotiate a good Brexit deal for Britain."