Almost 800 families remain in bed and breakfast and other temporary accommodation in Birmingham as the city council battles to cope with a sharp increase in the number of people declaring themselves homeless.

Between April and October this year the council provided 1,650 people with rooms, a figure boosted by a sudden rise in 16 and 17-year-olds forced onto the streets by their parents, relatives or friends.

New figures show that only half of those applying for emergency accommodation are granted homelessness status, forcing the council to house them. There are signs that the backlog of applicants waiting for a decision is diminishing as the local authority throws more resources at the problem.

Strategic director of housing Elaine Elkington said applications continued to rise, but had fallen from a peak in July and August.

She said that private landlords have offered the council 55 new properties for homeless people in the past two weeks.

Ms Elkington explained that council cash was being used to support homeowners at risk of eviction due to mortgage arrears.

A homelessness prevention fund has also been established by the council to provide money for key deposits and rent bonds for families and individuals who would otherwise be unable to find rented accommodation.

With a 140 per cent increase in homelessness in the past year, city officials are bracing themselves for the impact of Government housing benefit cuts.

Ministers are proposing a £400-a-week limit for the largest homes or £250-a-week for one-bedroom flats.

The National Housing Federation is warning that Government plans to force up social housing rents will backfire badly. Thousands of tenants will be “trapped on benefits” because they will be unable to afford the new rent levels, the organisation claimed.

It has forecast that a typical household with a couple and three children age below 16 on a rent of £85 per week would need to earn about £30,000 to come off housing benefit.

On a rent of £135 a week, the same family would need an income of about £38,000. On a rent of £250 per week, this rises to £47,000.

Ministers plan to deliver 155,000 new low cost homes across the country between April 2011 and March 2015.

However, instead of funding the homes through the social housebuilding budget – allied to private money raised by housing associations, who build social homes – they plan to pay for all the homes beyond those already earmarked under the last Government’s spending plans through increasing rents by up to 80 per cent of local market value.

The Government has signalled that it expects tenants who move into newly-built homes will be placed on short-term tenancies – effectively meaning the end of lifetime tenure in social housing.

The Federation’s West Midlands spokesman Paul Williams said: “The real answer to current concerns over housing benefit, and the intensifying housing crisis, is to allow housing associations to continue building social homes at scale. However, under this model no new real social homes will be built over the course of this Parliament beyond those already in the pipeline.

“The new funding model for low cost housing is predicated on high rents, instead of on an adequate capital budget, and this means that the freedom of housing associations to respond to need will be cut from beneath their feet.

“Housing associations wanted the flexibility to build a mix of homes at intermediate rents and social rents – but now the Government has imposed solution which replaces that mix with high-cost, near-market prices across the board.”

Birmingham’s largest private social landlord has said it may have to cut its building programme by 80 per cent.

Midland Heart, which manages more than 12,000 homes in Birmingham alone, said the reduction of the social housing budget from £8.4 billion to £4.5 billion for 2011 to 2014 would have a devastating effect on its customers.

Chief executive Tom Murtha said the Government’s policy was flawed and based on rental calculations in London that were not applicable to the region.