Developers have warned that Milton Keynes council is putting its groundbreaking infrastructure funding deal with the private sector at risk.

The authority is demanding more affordable housing, and is asking developers to meet tougher environmental standards. This is on top of the £20,000 per house “roof tax” that it has agreed for the growth zones to the east and west of the town.

Roger Humber, who is co-ordinating the Milton Keynes Forward consortium of developers and landowners, warned that the extra costs involved would reduce the amount developers had available to pay the roof tax.

Council leader Isobel McColl said the council’s previous policy, under which social units made up 5% of new homes provision, underestimated housing need in the town.

In a separate initiative, Milton Keynes is charging developers the UK’s first “carbon tax” if schemes are not carbon neutral.

Developers are expected to pay about £200 for each tonne of carbon dioxide produced by their dwellings. The tax is obligatory for schemes with more than five dwellings, or non-residential schemes bigger than 1000 m².