The British government said Wednesday it plans to allow its broadcast regulator to police the internet and issue substantial fines when social media giants fail to remove "online harm".

Media minister Nicky Morgan told parliament she was "minded to" give the Office of Communications (Ofcom) the powers to oversee online user-generated content.

But she said the expanded agency -- dubbed the "first internet watchdog" by UK media -- would lack the power to take down offensive posts or block platforms that violate "their duty of care".

Those suggestions were outlined in a set of proposals published last April by the government of former prime minister Theresa May.

Prime Minister Boris Johnson took over in July and focused first on navigating the Brexit crisis.

But Britain safely left the European Union last month and his government is now preparing to stamp its own vision on the country.

Morgan and Interior Minister Priti Patel published a report outlining Ofcom's "power to issue warnings, notices and substantial fines" to companies "that facilitate the sharing of (abusive) user-generated content".

The two senior ministers stressed they were equally conscious of respecting freedoms of expression and remaining a "pro-technology government".

"We will not prevent adults from accessing or posting legal content, nor require companies to remove specific pieces of legal content," they wrote.

"The new regulatory framework will instead require companies, where relevant, to explicitly state what content and behaviour is acceptable on their sites and then for platforms to enforce this consistently."

Ofcom was established in 2002 and began to formally oversee television and radio the following year.

But Britain has no official internet or social media regulator and is looking for ways to stop harmful online material from reaching children.

The issue gained added urgency when a British schoolgirl killed herself in 2017 after following a series of accounts about suicide and depression on Instagram and Pinterest.

"Two thirds of adults in the UK are concerned about content online, and close to half say that they have seen hateful content in the past year," Wednesday's report said.

The British government is moving to tackle 'online harm'
The British government is moving to tackle 'online harm' AFP / DENIS CHARLET

Social media giants such as Facebook want governments to adopt a common rulebook and oversight bodies that could take the pressure off their own management teams.

"New rules are needed so that we have a more common approach across platforms and private companies aren't making so many important decisions alone," Facebook said in response to Wednesday's report.

"Any new rules need to protect people from harm without undermining freedom of expression," it added.

The big tech companies have said they also want the government to clarify how "legal content" is defined.

The Internet Association lobby, which represents companies such as Amazon and Google, said it had several "issues of concern" about Britain's plan.

These include "the scope of regulation, treatment of legal but potentially harmful content, and enforcement powers," its UK chief Daniel Dyball said.

The government has been consulting top social media managers about its proposals for over a year.

Britain's role in drafting a universal solution was boosted by Mark Zuckerberg's appointment in 2018 of former UK deputy prime minister Nick Clegg as Facebook's head of global affairs and communications.

Clegg and Zuckerberg are now setting up an oversight board at Facebook that would issue final rulings on contentious content.

The UK report said social media executives rebelled at the idea of London fining individual managers who fail to respond to the regulator's warnings.

The proposal was seen as a measure of last resort by May's media minister.

"Senior manager liability emerged as an area of concern," Wednesday's report said.

"Discussions with industry highlighted the risk of potential negative impacts on the attractiveness of the UK tech sector."

The government said it will set out its final proposals in the coming months.