The organisation which represents England’s housing associations, warns that, without immediate action, only about 1.6m will be delivered by the deadline and it could take until 2029 for the rest to be built.

David Orr, the chief executive of the NHF, issued the stark warning at the federation's annual conference in Birmingham.

Federation chief executive David Orr said: "With the global credit crunch worsening, and conditions getting tougher for all housebuilders, it is time to recognise the very commendable 2020 target is now almost impossible.

"The climate for housebuilding has changed beyond all recognition, for private developers and social house builders. The number of homes being built is falling, and we need the government to take further action."

In 2007 167,577 new homes were built in the private and public sector. This year the figure could fall to 100,000.

Mr Orr warned that housing associations, which depend on private borrowing to top up government grants, would find it harder to raise money.

The federation wants the government to increase the grant available for each new housing association home to cover the private finance shortfall.

It also wants more measures to speed up the planning process so that properties can be built faster.