Theresa May has called on social media giants to stop their platforms becoming the "first choice" for paedophiles and terrorists.

In a speech at the World Economic Forum in Davos, the Prime Minister said tech companies need to ramp up their efforts in removing content that spreads child abuse or promotes extremism.

She also called on investors to put pressure on internet companies to crack down on criminals and terrorists using their platforms.

May cited a recent survey in the UK which found that seven in 10 people believe social media companies don't do enough to stop illegal or unethical behaviour on their platforms or prevent the sharing of extremist content.

"These companies simply cannot stand by while their platforms are used to facilitate child abuse, modern slavery or the spreading of terrorist and extremist content," May said.

"Earlier this month a group of shareholders demanded that Facebook and Twitter disclose more information about sexual harassment, fake news, hate speech and other forms of abuse that take place on the companies’ platforms.

"Investors can make a big difference here by ensuring trust and safety issues are being properly considered. And I urge them to do so."

The Prime Minister also stressed that smaller platforms can also quickly become home to criminals and terrorists, adding that "no-one wants to be known as 'the terrorists' platform' or the first choice app for paedophiles".

May also used her speech to stress that the UK needs to "make sure that our employment law keeps pace with the way that technology is shaping modern working practices".

She said: "Take the example of Uber – a ground-breaking use of technology that has radically changed how people move around in cities across the world. But also a company that has got things wrong along the way – with safety issues and concerns over the protections for its workers.

"The answer isn’t to shut Uber down but rather to address those concerns, and to establish and enforce the standards and protections that can make this technology work for customers and employees alike."

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May also said in her speech that she wanted to make the UK a world leader in innovative technologies, including artificial intelligence (AI).

However, she stressed that new norms and regulations must be development to ensure that AI is deployed in safe, ethical and innovative ways.

"We are absolutely determined to make our country the place to come and set up to seize the opportunities of artificial intelligence for the future," May said.

The Prime Minister's speech at Davos comes just a few days after the Government unveiled plans to establish a new unit to combat 'fake news'.

The new National Security Communications Unit will be "tasked with combating disinformation by state actors and others".