Social media companies will face fines of billions of pounds if they do not remove and limit the spread of harmful content including antisemitic posts, the government has announced.

The Online Harms Bill sets out the strict new guidelines on the removal of illegal content such as hate speech, terrorist material and child sexual abuse,  which sites must obey or face being blocked in the UK.

Ofcom is also confirmed as the regulator of the bill, with the power to levy unprecedented fines of up to £18m or 10 per cent of global turnover.

“Today Britain is setting the global standard for safety online with the most comprehensive approach yet to online regulation,” said Digital Secretary Oliver Dowden ahead of his statement to the House of Commons on Tuesday.

In July, Mr Dowden told the JC that Twitter’s failure to deal with a series of antisemitic posts by rapper Wiley lasting 48 hours was “yet more evidence that self-regulation isn’t working” — and has confirmed the “the government must and will step in.”

He pledged that the Online Harms Bill, which was first proposed by Theresa May's government in April 2019,  would “impose tough penalties on the well-resourced social media giants”.

Outlining the proposals Mr Dowden told the House of Commons on Tuesday the government were taking measures “to guard against things like antisemitic abuse.”

But he added that legislation would seek to avoid allowing the government or social media companies the chance to put their “world view onto their output.”

Mr Dowden said there “must be reasonable grounds” for removing hateful matrial from the web.

One senior communal leader said they were “cautiously optimistic” ahead of the proposals announced on Tuesday.

They said they hoped there would be further clarity on what constituted legal but harmful online activity.

But they pointed out that the government had backed down on one suggestion – which appeared in the initial consultation - to bring criminal sanctions against individual executives at the social media giants.

The legislation includes provisions for such penalties, but that power will need to be separately introduced by Parliament via secondary legislation.

The government says it plans to introduce that legislation only if companies fail to take the new rules seriously.

The communal source told the JC they were also pleased that freedom of expression also appeared to have been taken into consideration.

Ofcom will be given ultimate say over where to draw the line and what offences warrant its toughest sanctions.

Based on current earnings, it could fine Instagram's parent company Facebook $7.1bn and YouTube's owner Google $16.1bn for any failure to remove and limit harmful content.

Bigger companies would have added responsibilities, including having to publish regular transparency reports about steps taken to tackle online harms, and being required to clearly define what types of "legal but harmful" content they deem permissible.