Speaking on the BBC's Andrew Marr show, health secretary Matt Hancock said: "If we think they need to do things they are refusing to do, then we can and we must legislate."

He earlier called on social media giants to "purge" material promoting self-harm and suicide in the wake of links to a teenager's suicide.

Asked if social media could be banned, Mr Hancock said: "Ultimately parliament does have that sanction, yes" but added: "it's not where I'd like to end up".

Molly Russell, 14, took her own life in 2017 after viewing content about suicide on social media.

She was found dead in her bedroom in November 2017 after showing "no obvious signs" of severe mental health issues.

Her family later found she had been viewing material on social media linked to anxiety, depression, self-harm and suicide.

Speaking to the BBC, her father said he believed Instagram "helped kill my daughter".

Russell also criticised the online scrapbook Pinterest, telling the Sunday Times: "Pinterest has a huge amount to answer for."

Instagram responded by saying it works with expert groups who advise them on the "complex and nuanced" issues of mental health and self-harm.

Based on their advice that sharing stories and connecting with others could be helpful for recovery, Instagram said, they "don't remove certain content".

Facebook, which owns Instagram, said earlier it was "deeply sorry".

The internet giant said graphic content which sensationalises self-harm and suicide "has no place on our platform".

Hancock explained: "Lots of parents feel powerless in the face of social media. But we are not powerless. Both government and social media providers have a duty to act.

"I want to make the UK the safest place to be online for everyone - and ensure that no other family has to endure the torment that Molly's parents have had to go through."