This weekend Ed Miliband will deliver a speech to Labour’s National Policy Forum in Birmingham warning that house builders with planning ‘must use it or lose it’.

Labour has seized on figures that show planning permission has been granted for 400,000 homes in England that have not been built.

The speech is part of a move by Labour to focus the political debate on house building and highlight the Coalition Government’s failure to adequately tackle the housing crisis.

In a leak of his speech, Miliband says: “Permission to build should mean land-owners build. If there is unnecessary hoarding, developers should be encouraged to do what they are in business to do: build houses.”

“We have to be willing to confront some of the obstacles to house building.

“Across our country, there are firms sitting on land, waiting for it to accumulate in value and not building on it. Land-owners with planning permission, who simply will not build.

He warned: “We have to change that. That’s why as part of our Policy Review we will consult in the coming months on how to get that building started.

“All options should be on the table, including giving local authorities real power to say to the worst offenders that they should either use the land, or lose the land.

Miliband will highlight new figures published this week by Shelter showing young people who work hard are locked out of buying new homes for up to 30 years because of sky-high property prices fuelled by decades in which Britain has failed to build enough houses.

Despite surging profits among volume house builders and signs of a recovery in prices, the last quarter saw just 18,380 homes completed by the private sector – the lowest quarter in 23 years.

New figures also show the average time taken to complete a private development has risen from 20 months in 2008 to 25 months in 2012. In London it is 30 months.