Chancellor George Osborne should think about cutting the top rate of income tax, Boris Johnson said as he praised India for having a more attractive regime for entrepreneurs.
The London Mayor said the Chancellor should "brood" on whether the top rate of tax - which currently stands at 45% - should be cut.
He said he met Mumbai-based businessmen on Friday morning, who asked him whether London could be made more attractive to foreign investors through lower rates of tax and less regulation. In reply, Mr Johnson said the tax regime "needed to be looked at".
Speaking at the Bombay Stock Exchange on the final day of his tour of India. Mr Johnson said: "You've got tax rates here of only 30% - a point George Osborne might like to brood on.
"It's 10% for freelance income, and of course you have a market of about 600 million people under 25."
In interviews with reporters afterwards, he added: "One businessman said to me this morning that he loved London, he loved the quality of life in London. There are so many attractions of living in London that you can't find anywhere else. That is a very high card.
"But another businessman asked about making London more attractive in terms of tax and regulation and certainly the tax regime. As I have said many times before, that needs to be looked at."
After an hour and a half of speeches at the stock exchange, Mr Johnson posed with the bull statue at its main entrance, gripping its horns as if he was a rodeo rider desperately clinging on.
He then headed to the Gateway of India, an 85ft (26m) basalt arch which stands in Mumbai's harbour, to pose for pictures with a British-made Brompton bike.
During the afternoon, Mr Johnson will head to a television studio for an interview with India's equivalent of David Letterman when he appears on Times Now with Arnab Goswami.