Theresa May is warning the UK is gripped by a spate of terror attacks after seven were killed and nearly 50 injured by an attack on London Bridge on Saturday night.

Offering a stark assessment of the threat against Britain, the Prime Minister claimed there is 'far too much tolerance of extremism' in the UK, saying 'enough is enough'.

Speaking after chairing a meeting of the Cobra security committee, May said internet companies must not allow extremism to spread and said 'difficult' conversations were needed to tackle 'safe spaces in real world'.

In a statement that marked a change of tack from previous speeches after terrorist attacks in Manchester and Westminster in the last three months, the PM said new laws were needed and harsher prison sentences for perpetrators.

Islamist militancy was the thread that linked all three attacks, she said.

'It is an ideology that is a perversion of Islam and a perversion of the truth,' she said. 'Defeating this ideology is one of the great challenges of our time. But it cannot be defeated through military intervention alone.'

She added: 'It is time to say enough is enough. Everybody needs to go about their lives as they normally would. Our society should continue to function in accordance with our values. But when it comes to taking on extremism and terrorism, things need to change.'

She went on: 'As terrorism breeds terrorism and perpetrators are inspired to attack, not only on the basis of carefully constructed plots after years of planning and training, and not even as lone attackers radicalised online, but by copying one another and often using the crudest of means of attack.'

Calling for more action both in the UK and overseas she said: 'While we have made significant progress in recent years, there is – to be frank – far too much tolerance of extremism in our country.

'So we need to become far more robust in identifying it and stamping it out across the public sector and across society. That will require some difficult, and often embarrassing, conversations.

'But the whole of our country needs to come together to take on this extremism, and we need to live our lives not in a series of separated, segregated communities, but as one truly United Kingdom.'

The general election campaign is suspended for today but May confirmed polling day would not be postponed and campaigning would resume on Monday.

'Violence can never be allowed to disrupt the democratic process. So those campaigns will resume in full tomorrow and the general election will go ahead as planned on Thursday.

'As a country our response must be, as it has always been, when we have been confronted by violence, we must come together. We must pull together. And united, we will take on and defeat our enemies.'