A man holds a smartphone with the icons for social networking apps on the screen.

Britain proposed new online safety laws on Monday that would slap penalties on social media companies and technology firms if they fail to protect their users from harmful content.

Easy access to damaging material particularly among young people has caused growing concern worldwide and came into the spotlight in Britain after the death of 14-year-old schoolgirl Molly Russell, which her parents said came after she had viewed online material on depression and suicide.

Governments across the world are wrestling over how to better control content on social media platforms, often blamed for encouraging abuse, the spread of online pornography, and for influencing or manipulating voters.

Global worries were recently stoked by the live streaming of the mass shooting at a mosque in New Zealand on one of Facebook's platforms, after which Australia said it would fine social media and web hosting companies and imprison executives if violent content is not removed "expeditiously".

In a policy paper widely trailed in British media, the government said it would look into possibly using fines, blocking access to websites, and imposing liability on senior tech company management for failing to limit the distribution of harmful content.

It would also set up a regulator to police the rules.

TechUK, an industry trade group, said the paper was a significant step forward, but one which needed to be firmed up during its 12-week consultation. It said some aspects of the government's approach were too vague.

"It is vital that the new framework is effective, proportionate and predictable," techUK said in a statement, adding not all concerns could be addressed through regulation.

Facebook said it was looking forward to working with the government to ensure new regulations were effective, repeating its founder Mark Zuckerberg's line that regulations were needed to have a standard approach across platforms.