Boris Johnson has warned David Cameron and Theresa May not to put the "vibe" of London that attracts skilled people from abroad at risk by clamping down too much on immigration.
In a thinly-veiled message, the London Mayor told the Huffington Post UK: "You've got to be open to talent and London is a great place to live."
Johnson's remarks came as research by the anti-immigration lobby group Migrationwatch suggested that immigrants have costed the UK more than £22 million a day for 17 years, in analysis that academics dismissed as "complete guesswork"".
Speaking at the launch of a "Techhub" workspace for entrepreneurs, Johnson said: "We've got the lunar pull of London. People just want to be here, they're attracted by the sheer agglomeration of talent...they come for the vibe in London."
Johnson is one of the few senior Tory politicians to defend immigration, with his remarks coming days after Lib Dem business secretary Vince Cable hit out at "scare stories" about immigration.
Cable recently warned that the coalition's pledge to cut net migration to "tens of thousands" was "impractical' and that a big increase in net migration was "good" for the economy.
However, asked by HuffPostUK whether he agreed with Cable's comments about net migration, Johnson diplomatically insisted: "I agree with David Cameron on all points."
The Prime Minister’s claim provoked derision from business groups, which stressed the economic and fiscal benefits of net migration as a whole.
John Wastnage, head of labour market policy at the British Chambers of Commerce, told the Huffington Post UK: “The whole of the government’s immigration policy is very damaging to the economy. Immigrants are more likely to work, use fewer services and claim less benefits. Our own research shows employers hire immigrants because of their skills, not because they cost less.”