Boris Johnson blamed as number of new homes built falls to a 20-year low

Boris Johnson's housing plans came under attack today as it emerged that fewer homes were built in London last year than at any time over the last 20 years.

Work started on 11,480 homes, the lowest number since 1990, with only 4,180 in the "affordable" category, official figures show. The chronic housing shortage is set to dominate the next mayoral race.

Former mayor Ken Livingstone said Tory Mr Johnson should be "ashamed" and called on him to reintroduce Labour's target that 50 per cent of new housing should be affordable.

Mr Johnson claims he has delivered 26,000 affordable homes and is on course for 50,000 by 2012, but has delayed his pledge by a year in the economic downturn.

The Department of Communities and Local Government figures show 27,730 homes have been started since Mr Johnson came to power in 2008. In Mr Livingstone's eight years, 156,310 were begun.

Mr Johnson's spokesman said: "In the worst recession for a generation, the Mayor has ensured house building continues."

But Mr Livingstone said: "He is failing hundreds of thousands of Londoners denied the chance of an affordable home."