Boris Johnson has made an extraordinary appeal for billionaires' wives to sue for divorce in London.
The capital's mayor insisted the capital was the perfect place for "injured spouses" to take their wealthy other halves "to the cleaners".
The call came in a speech to the CBI conference, in which he also delivered a series of jibes at coalition policies.
He dismissed "absurd" proposals for a tax raid on owners of expensive homes, warning that high rates of personal taxation would make Britain less competitive. He also again demanded that a third runway be ruled out at Heathrow Airport, and mocked turnout in the recent police and crime commissioner (PCC) elections.
Hailing the capital as the "chief glory of the UK economy", Mr Johnson said it dominated the world in the areas of law, property, insurance and accountancy.
"I would never encourage anyone to sue, but if one oligarch feels defamed by another oligarch, it is London's lawyers who apply the necessary balm to the ego," he said. "I have no shame in saying to the injured spouses of the world's billionaires if you want to take him to the cleaners... take him to the cleaners in London. Because London cleaners will be grateful for your business."
Speaking on the BBC's Andrew Marr show on Sunday, Business Secretary Vince Cable revived the Liberal Democrat drive for a so-called 'mansion tax'. He indicated that some kind of levy on property was being considered for inclusion in Chancellor George Osborne's crucial autumn statement, despite the Tories previously pouring cold water on the idea.
But Mr Johnson said: "I am afraid that high rates of personal taxation are likely to make us less competitive. We should have taxes that are low but fair and it is absurd to be suddenly whacking up taxes on cash-poor people who happen to inhabit expensive houses in London when firms like Google are paying zero.
"Neither arrangement strikes me as being fair and so Google and co face a very clear choice - they can either change their tax arrangements or do much more to serve our society by visibly taking on 18-24 year olds who are out of work."
Asked whether the Prime Minister backed Mr Johnson's call for wealthy foreigners to settle their disputes in the London courts, a Downing Street spokeswoman said: "We are trying to dissuade libel tourism as a point of principle."