As many as 70,000 jobs in London's financial services sector could be lost due to the "catastrophic" effects of Brexit, a new report has warned.

And the City also risks the loss of the "creative edge, liveability and variety" resulting from its status as a magnet for workers, students and visitors from around Europe and the world, warned the report by the Centre for London think tank.

The group called for Mayor Sadiq Khan to be given a "prominent" input into Brexit negotiations, as part of a Convention of City Leaders including mayors of major cities like Manchester, Glasgow, Bristol and Newcastle which stand to lose out from EU withdrawal.

Among measures to limit the damage to cities from Brexit, the government should introduce a regional migration system, with different work permit quotas according to areas' particular skills needs, the report said.

In London's case, this should include a one-year City Maker Visa to allow EU citizens to live for a year in the capital while looking for work or start-up opportunities and an extended two-year working holiday visa for young Europeans, with fast-track work permit applications for both groups.

The report, entitled Open City, said the blow to financial services from Brexit would be "significant but not mortal".

And it said that London was in some ways less exposed than other parts of the UK to the risks of Brexit, because it already had well-developed links with other world cities outside the EU.

But it warned: "From other perspectives, London is far more exposed: our universities, hotels, restaurants, offices and building sites are powered by students and workers from across the EU to a far greater extent than the rest of the country.

"And our global city service sectors need urgent clarity on how access to the Single Market will be regulated."

It added: "Falling out of the Single Market without a comprehensive trade deal or adequate transitional arrangements would be catastrophic for many London businesses, as would the sudden loss of EU workers."

And the capital is also threatened by the potential harm Brexit will inflict on its ability to attract the young students, musicians, artists and entrepreneurs from around the world who will go on to be the decision-makers and superstars of the future and act as "lifelong ambassadors for London".

"The longer-term risk is more subtle but no less serious - the erosion of the creative edge, liveability and variety that distinguishes London from so many other cities that can offer well-equipped offices and international airports," the report said.

"London needs to remain open and also needs to become more affordable and liveable.

"It needs to continue to attract students from across the world, and to speak out against attempts to hit arbitrary immigration targets by cutting their numbers."

The report raised the possibility that last year's vote for Brexit was in part driven by resentment outside the capital of London's dominant position in the UK.

It warned: "It may be that resentment of London was a factor in the EU referendum, but neither capital nor country can afford for London to decline economically or to retreat from international engagement."