Sir Sadiq Khan has blamed Russia, China and the US for generating AI content claiming London is in decline.
The Mayor of London took to social media to criticise the online content and linked to research commissioned by City Hall that found a surge in such posts over the past two years.
Sir Sadiq said: "You've got state actors, claiming that evidence had emerged of Russian and Chinese involvement alongside backers of the Make America Great Again movement in the United States."
He added: "Secondly, we've seen individuals and companies trying to monetise and make profit from division."
"My anxiety is, decent people start believing these lies, this dystopian image of London being in decline, that we're a dangerous city, that there is no law and order."
The Mayor doubled down on these claims, releasing a statement on his X account.
He wrote: "Outrage generates clicks, which is why you'll have noticed a surge in online content talking London down.
"Be vigilant: so much of what we see online is far from real."
Sir Sadiq Khan has Russia, China and the US for generating AI content, claiming London is in decline
|PA
Sir Sadiq linked to a BBC article titled "Anti-immigration AI videos traced to overseas fakers."
It comes after a surge in Facebook and Instagram accounts producing anti-immigration material using artificial intelligence.
Despite presenting themselves as pro-British voices, many of these pages are operated by people based thousands of miles from the UK, the publication claims.
One page, named "Great British People", which claims to originate from Yorkshire and has attracted 1.3 million views for its most recent video, is thought to be controlled by someone in Sri Lanka.
LATEST DEVELOPMENTS
An AI video showing London in decline
|TIKTOK/TONYJAMESWATT
Other account operators have been traced to Vietnam, the Maldives, the United States and various European nations, with some linked to Iran and the UAE.
GB News presenter Matt Goodwin described the capital as a "jewel in Britain's crown", but claims London is now in decline.
He said: "It no longer feels like the same city. Millions of Londoners agree with me."
Mr Goodwin added: "There is one factor above all that is changing London in their eyes for the worse, and that is mass uncontrolled immigration."
An AI video showing rats running around London
|TIKTOK/PEACEROADMAN
These accounts have accumulated hundreds of thousands of views with fabricated footage depicting scenes such as the House of Commons filled with men in traditional Arab dress implementing Sharia law.
One account boasting more than 20 million views presents AI-generated walking tours through British cities in 2050, showing Liverpool, London and Birmingham as rubbish-strewn and chaotic, with streets lined by people in Islamic clothing and stalls marked "Halal".
Sir Sadiq expressed concern to the BBC that "decent people start believing these lies, this dystopian image of London being in decline, that we're a dangerous city, that there is no law and order."
He called on social media platforms to amend their algorithms to stop "rewarding poison and division" and to clearly label AI-generated material.
Our Standards: The GB News Editorial Charter