Sadiq Khan has read out some of the racist and abusive tweets he has received since being elected London Mayor to illustrate the need to clean up social media.
In a major speech to the South by Southwest Conference in Texas, the Labour politician revealed he had been abused as a 'gay muzzie terrorist' and threatened with murder.
Other more bizarre messages suggested Mr Khan 'looks like a pigeon' or a 's*** stunt double for Jose Mourinho'.
Mr Khan said he did not want or need sympathy but demanded tougher action from social media giants - warning they must face stricter laws if they failed to act.
The Mayor also accused politicians of a 'dereliction of duty' by failing to ensure the tech revolution has worked for everyone in society.
Mr Khan warned Uber and other tech firms that all companies 'must play by the rules' in the markets in which they operate.
The Labour mayor is the first British politician to give a keynote speech at South by Southwest.
Most of the messages highlighted by Mr Khan are months old and were still visible on Twitter the day after his speech.
Mr Khan read out the abuse and said: 'I could go on and on, but I won't.
'I don't read these out to be portrayed as a victim, or to ask for sympathy.
'But ask yourself this - what happens when young boys and girls from minority backgrounds see this kind of thing on their timelines – or experience it themselves?
'Or someone thinking about becoming a politician?
'And what about young girls and women who are being driven from these platforms – reversing our long fight for gender equality?'
He also raised concerns over social media's role in influencing elections and referendums, spreading fake news and enabling extremists to radicalise and brainwash others.
'Facebook, Twitter and other platforms are finally starting to react to the criticisms and are developing technology to make sure the reporting process becomes quicker and more effective,' he is expected to say.
'But with the skills and resources these companies have at their disposal, I believe it's possible to go further and faster.'
If this does not happen, Mr Khan will say that more countries 'will start to follow or go further than what Germany has done'.
Germany has recently introduced tough new laws so that social media companies face large fines if they fail to quickly remove things like hate speech.
He said: 'There must be greater responsibility taken by some tech companies for the impact they're having on the world.
'And, crucially, no business or industry should ever consider itself above the local rules, or laws set by democratic processes.
'In London, we've been clear with Uber and other companies that everyone, no matter how big or small, must play by the rules. No exceptions.
'Our economies have always needed new regulations in place to meet the needs of workers and consumers when the environment changes. Evolving economies must mean evolving regulation, and today is no different.'
Mr Khan accused politicians and governments of 'sitting on their hands while the tech revolution has happened around them'.
He added: 'It must ultimately fall to government - working with tech businesses and leaders - to ensure that this revolution is not detrimental to our long-term progress.
'There's been a dereliction of duty on the part of politicians and policymakers to ensure that the rapid growth in technology is utilised and steered in a direction that benefits us all.'