London mayor Sadiq Khan says the city must be given more autonomy in order to ride out  the economic uncertainty created by Britain's decision to leave the EU.

"But it's now absolutely crucial we move fast. We can't hang around for the outcome of the EU negotiations before we give Londoners more control. It needs to happen now," Khan said.

While Britons voted 52 to 48 percent to leave the EU bloc last week, London overwhelmingly backed remaining. Since then, more than 175 thousand people have signed an online petition calling for London to become an independent city-state.

Khan, who campaigned for Britain to stay in the EU, is seeking more control over tax raising powers, and other areas including business, transport, housing, health and policing. The mayor also said the UK must remain a member of the European single-market during negotiations with the bloc.