Messages telling Sadiq Khan “blow himself up” and other racist online abuse were read out by the London Mayor as he demanded action from social media firms to tackle hate speech.

Speaking at the South by Southwest (SXSW) conference in Austin, Texas, Mr Khan read out messages including one saying "kill the Mayor of London and you will be rid of one Muslim terrorist".

Another message received on Twitter said "deport all Muslims and make London white again" while a third said "I wish Sadiq Khan would blow himself up like they all do".

The Mayor said he was not seeking sympathy but suggested the level of abuse could deter other people from minority backgrounds from entering politics.

Mr Khan urged the likes of Facebook and Twitter to improve their response to criticism, or face the possibility of further regulation.

Mr Khan said: "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?"

Mr Khan 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 said.

"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.

Mr Khan accused politicians and governments of "sitting on their hands while the tech revolution has happened around them".

He will add: "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."