The housing secretary Robert Jenrick has attacked London Mayor Sadiq Khan’s plans to introduce rent controls and his record on delivering new homes in a scathing letter.

Jenrick says that he is using his legal powers to direct Khan to make changes to his London Plan, which he says is inconsistent with national policy and he insists that it cannot be published until these amendments have been made.

He attacks the Mayor’s controversial plan to introduce rent controls as “empty threats”, since “by law you cannot introduce without government consent”.

“As we all know, evidence from around the world shows that rent controls lead to landlords leaving the market, poorer quality housing and soaring rents for anyone not covered by the controls,” Jenrick argues.

He says: “Housing delivery in London under your mayoralty has been deeply disappointing, over the last three years housing delivery has averaged just 37,000 a year; falling short of the existing Plan target and well below your assessment of housing need. 

“Over the same period, other Mayors such as in the West Midlands have gripped their local need for housing and recognised the opportunities this brings, leading significant increases in the delivery of homes.

“Since you became Mayor, the price of an average new build home in London has increased by around £45,000, reaching £515,000 in 2018, 14 times average earnings. 

“Clearly, the housing delivery shortfall you have overseen has led to worsening affordability for Londoners; and things are not improving, with housing starts falling a further 28 per cent last year compared to the previous.”

Jenrick goes on to criticise specific instances where he argues that the Mayor has failed.

He says the Mayor’s Development Corporation had to turn away £250m of funding “because of your inability to work successfully with the main landowner” and that the Mayor turned down a further £1bn in government funding “because of the support and oversight that would accompany this”.

Jenrick says the mayor’s plan is only likely to deliver 52,000 homes a year instead of the 66,000 that are needed.

He claims Khan’s plans are likely to favour the creation of one-bedroom flats leading to more people leaving the capital when they want to have a family.

Jenrick says the mayor’s proposals will make the planning process even more complicated and slow down the delivery of housing, because of over-prescriptive and “cumbersome” details which includes “policies on things as small as bed linen”.

Khan has previously said his re-election bid is a referendum on his rent controls policy and that the Prime Minister must uphold democracy and legislate for powers to implement rent controls in the capital if Khan is voted back in.

A spokesman for Khan says: “The mayor makes no apologies for trying to deliver genuinely affordable housing in the capital while at the same time protecting and enhancing the green belt. 

“The Secretary of State is trying to run roughshod over the mayor’s efforts to finalise a London Plan, which will deliver for Londoners and deliver on pledges from the mayor’s manifesto.

“The Secretary of State needs to realise that London is best served by the government devolving further funding and powers to the capital to build the affordable homes it urgently needs, instead of taking this heavy-handed approach.”