Sadiq Khan’s proposed rent controls would be “a level of regulation unseen in any developed country”, according to a housing policy researcher.

Kath Scanlon, assistant professorial research fellow at the London School of Economics, said the policy would have “dramatic unintended consequences” and landlords would stop renting out their properties.

There are now 2.4 million renters in the capital, and rents are rising faster than wages, according to research by City Hall.

The Mayor cannot currently bring in rent controls, though he has called on the Government to devolve the powers to London.

But speaking at the London Assembly’s Budget and Performance committee yesterday (Thursday) Ms Scanlon said the Mayor’s plans would not work as hoped.

She said: “The Mayor’s proposals as I understand them are not simply to cap rents at existing levels, or to regulate rises of rents within leases, but to reduce rents from their current levels.

“I’ve done several studies of international rent regulation and I’ve never seen that policy anywhere.

“That would be a level of regulation unseen in any developed country I think, and would have really dramatic unintended consequences.”

She added: “Landlords would simply decide they were no longer going to rent their properties.”

Mr Khan has said that if rent control powers were devolved, he would make a register of all private landlords in the city.

He would also set up a Private Renters’ Commission to gradually reduce rents.

His policy has support in the capital, with 68 per cent of Londoners in favour of rent control or stabilisation, according to a YouGov poll.

But Conservative mayoral candidate Shaun Bailey said rent controls would drive landlords out of the market and lower standards in the city’s existing housing stock.

He said: “Sadiq Khan knows this, and doesn’t care. He just wants to ask for powers he knows the Government won’t give him so he can pick a fight. Meanwhile, it’s Londoners who will get left behind.

“The only answer to the plague of high rents and high house prices is to build more homes, something Mayor Khan has utterly failed to do.”

He added: “Rent controls are just false hope peddled by politicians who don’t want do the hard work of building the homes we desperately need.”

But James Murray, Deputy Mayor for Housing and Residential Development said people in the capital know rents are too high.

He said: “The Mayor’s plans set out how rent control would be carefully designed and introduced to bring down rents for Londoners whilst making sure there is investment in new and existing housing.

“Renters around the world from Berlin to New York are demanding change – Sadiq is determined to get the powers from our national government so he can make that change for Londoners.”