The Mayor of London believes the government has “watered down” its bill to protect tenants against the increasing costs of renting a house.

The proposed Tenants Fees Bill makes laws banning landlords and letting agents from making certain financial requirements to people looking to rent properties.

But today the Mayor of London, Sadiq Khan branded it a “missed opportunity” to protect private renters in the capital.

He called on the government to cap deposits at now more than three weeks rent but now ministers have proposed a six-week cap.

He said: “Rising rents, ongoing insecurity, and in too many cases poor quality housing makes the 2.4 million private renters in London amongst those worst-affected by the housing crisis.”

The Mayor also said that the proposed bill contains “loopholes” and formalises agents’ abilities to charge renters extra for basic services – such as responding to emergency call outs.

Mr Khan added: “By backtracking on proposals and watering down the strength of this Bill, Ministers are in danger of opening the door to an entirely new culture of exploitation, with the legislation left unfit for purpose and simply a missed opportunity to truly help renters.

“This is just one area of housing where Ministers are letting people down, both in London and across the country.”

Mr Khan and charities campaigning for better rent controls – Crisis, Generation Rent and Citizens UK have written a letter to the Prime Minister setting out how they think private renting needs to be reformed.

They have called on the Government to make certain amendments to the bill before it is passed.

The amendments include capping rental deposits at three weeks’ rent and writing so-called “default fees” such as emergency calls outs into tenancy agreements.

Analysis from City Hall found that renters in London need to find nearly £3,700 each time they move home, compared with the nationwide average of £2,000.

Chief executive of Crisis Jon Sparkes, commenting on the joint letter, said: “Thousands of people across England are trying to move on from homelessness, but they have no way of finding a home.

“This is a desperate situation, and it’s all the worse because our research shows that homelessness can be ended with the right policies in place.”