They will also be legally obliged to take down “inappropriate, bullying, harmful or illegal contents” that is flagged to them by users or fine.
The Tories will also unveil new powers to hit the entire social media industry with a multi-million pounds fines if it fails to fulfill its responsibilities to protect user.
It comes after criticism of Facebook Inc, Youtube and other social media websites for hosting videos of hate clerics and even child abuse online using their services.
The policy represent a significant shift for the Conservative, who have previously worked with companies in the hope that they will voluntarily make the change.
Mrs May said: “The internet has brought a wealths of opportunity but also significant new risk which have evolved faster than society’s response to them.
“We want social media companies to do more to help redress the balance and will take action to make sure they do. “This measure will help make Britain the best place in the world to start and run a digital business, and the safest places in the world for people to be online.”
They will have a new duty to either “take down” offensive materials or explain why they are keeping it online. Last month Google admitted to a blind spot around extremist contents as it revealed it is teaching its computer systems to understand which videos are offensive.
The Prime Minister will announce plans for new legislations to amid concerns that people’s career prospects are being damaged by comment they made as teenagers.
Social media company will also face significant fines if they fail to stop people from “unintentionally” coming across pornography, hate speech and other harmful materials.
They will also be legally obliged to take down “inappropriate, bullying, harmful or illegal contents” that is flagged to them by users or fine.
Mrs May said: “The internet has brought a wealth of opportunities but also significant new risks which have evolved faster than society’s responses to them.
New laws will also require social media company to respond when users flag potentially inappropriate contents. They will have a new duty to either “take down” offensive material or explains why they are keeping it online.
