A legal challenge is being lodged by Tower Hamlets Council against “devastating” plans to set affordable rent rates at 80 per cent of the market value.

London Mayor Boris Johnson last week passed plans to cap rents in “affordable homes” at that level as part of his ‘London Plan’ blueprint for the capital.

But Tower Hamlets - along with Islington, Southwark and Camden councils - argues that the cap is too high for new affordable housing.

Mayor Lutfur Rahman hit out at Mr Johnson’s “devastating” decision not to allow local authorities to set their own caps.

“We too want to maximise the levels of affordable housing being delivered, but our residents simply cannot afford rents of up to 80 per cent of the market rate,” he said.

“It’s time Boris Johnson listened to what councils are telling him about the different housing needs in their areas – there’s little point building new homes that local people can’t afford to live in.”

Tower Hamlets’ own recommendations would see rents for new affordable housing capped at 65 per cent of the market rate for one bedroom flats, and 50 per cent for four bedroom properties.

Mr Johnson’s plans were rejected by a majority of London Assembly members – but those opposed could not get the two thirds of votes needed to overturn the policy.

The Mayor’s office said affordable rents across London would average 65 per cent of the market value.

A spokesman added: “Rent controls across 33 different boroughs would simply have the negative effect of driving away vital investment and reduce the number of homes built - exacerbating London’s housing crisis.”