Theresa May should be "utterly ashamed" of her record on law and order, London Mayor Sadiq Khan said as he hit out at cuts to the emergency services.
In his Labour conference speech, Mr Khan highlighted £1 billion of real-terms cuts to Scotland Yard between 2010 and 2021 and claimed that police funding for counter-terrorism is set to fall by 7% over the next three years.
The mayor - who was initially denied a speech at the gathering in Brighton before a late change of plan - used his address to praise Jeremy Corbyn after clashing with the Labour leader in the past.
Mr Khan used his speech to praise the response of the emergency services to the terrorist attacks in the capital and the Grenfell Tower disaster.
But he accused the Tory government - led by former home secretary Mrs May - of overseeing a rise in crime after seven years of cuts to the emergency services, including the police, fire service, NHS and transport network.
He urged the Government to increase overall police funding in real terms at the Budget in November.
He said: "The Tories used to describe themselves as the party of law and order... well that sounds like a bad joke today. And frankly, as a former home secretary, Theresa May should be utterly ashamed of her record."
Labour leader Mr Corbyn was notably absent when Mr Khan was inaugurated as London mayor in 2016 and backed Owen Smith's leadership challenge.
But at the conference the mayor said: "We made huge progress in the general election and the credit for that goes to one person - the leader of our party - Jeremy Corbyn."
Comparing Mrs May's administration to the Conservative infighting at the end of Margaret Thatcher's rule, he said: "This all feels very familiar - a weak and divided Tory Government refusing to face up to the challenges ahead.
"Bickering and infighting over Europe putting our jobs and economy at risk. Chronic underinvestment in public services causing a crisis in our schools and hospitals. And crime on the rise. But conference, this isn't the 1990, this is now. It's like Back to the Future, but it isn't funny."