The outburst triggered a war of words between the Labour mayor and the Conservative-controlled council over the decision.
Khan said: “I am furious over Wandsworth Council’s planning committee’s decision last night to back a wholly unacceptable cut in the amount of affordable housing at Battersea Power Station.
“If we are serious about tackling London’s housing crisis, we need all councils in London to be pushing in the same direction. This decision has let Londoners down.
“As this was a change to planning consent granted under the previous mayor, I have no formal planning powers to stop it. However, I have made formal representations to Wandsworth Council urging them to withdraw the decision, and to work with me to secure the absolute maximum amount of affordable housing possible.”
The mayor’s statement was swiftly countered by a response from planning committee chairman and Conservative councillor Richard Field, who said the whole development would have been put at risk by failing to cut the affordable homes.
Field also defended the council’s record on building affordable homes and said the mayor had been invited to comment on it before the decision was taken.
“The escalating cost of restoring the power station building has pushed this entire development project into serious financial trouble and the committee had a very difficult choice between accepting a potentially lower number of affordable homes, or refusing the application and risk losing all of them,” said Field.
“This development also directly funds the Tube extension which is bringing 25,000 jobs to Battersea, so the stakes are extremely high.
“I believe we made the right choice and in doing so have safeguarded the delivery of thousands of other affordable homes across the Nine Elms regeneration area which are dependent on the northern line extension being delivered. This change also means that 386 affordable homes will now be built by the power station developer in 2020, two years earlier than previously planned.”
According to Field, Wandsworth delivered the second highest number of affordable homes among all 33 London boroughs and he also criticised the mayor for approving a development in Merton with only 9% affordable housing.