Expert have urged peers to halt the government's proposed "bedroom tax" amid claims it will have "disastrous" consequences.

In a blog for the Huffington Post UK, the Chief Executive of the National Housing Federation (NHF) David Orr says nearly three-quarters of a million families deemed to have a spare bedroom could be £676 a year worse off under plans to dock their housing benefit.

"This bedroom tax will have disastrous implications for a huge number of people already struggling to make ends meet in this tough economic climate, including grandparents, disabled people and smaller families," he warns.

Instead of tackling state spending, the NHF claim that it will hit teenagers and foster parents.

"Under the government's restrictive new rules, same sex teenagers up to the age of 15 will be forced to share a bedroom.

"And foster parents will be affected even where their bedrooms are occupied by foster children, who for benefit purposes do not count as part of the household."

The NHF has called on peers to support an amendment by Lord Best blocking the tax.

But Welfare reform minister Lord Freud said the situation was not "fair or affordable"

"It’s not fair or affordable for people to continue to live in homes that are too large for their needs when, in England alone, there are around five million people on the social housing waiting list and over a quarter of a million tenants are living in overcrowded conditions.

"It’s only right that we bring fairness back to the system and make better use of the social housing stock."