Private rents have become unaffordable in more than half of local authorities in England, research from Shelter has found.

The charity said average private rents are beyond the means of "ordinary" families in 55% of local authorities. Homes were found in these areas which cost more than 35% of the median average local take-home pay - the level considered by the Shelter Private Rent Watch report to be unaffordable.

Campbell Robb, chief executive of the housing and homelessness charity, said: "We have become depressingly familiar with first-time buyers being priced out of the housing market, but the impact of unaffordable rents is more dramatic.

"With no cheaper alternative, ordinary people are forced to cut their spending on essentials like food and heating, or uproot and move away from jobs, schools and families."

Shelter said that in the 10 years up to 2007, rents increased at one-and-a-half times the rate of incomes.

Private rents in 8% of local authorities in England were "extremely unaffordable" - with average rents costing 50% or more of full-time take-home pay. Just 12% of areas were affordable, with rents sitting below 30% of take-home wages.

The analysis was carried out on two-bedroom homes due to their common occurrence.

Housing Minister Grant Shapps said: "This Government recognises the importance of the private rented sector in providing accessible and affordable accommodation. We have stopped the imposition of excessive new red tape on the private rented sector, which would have pushed up rents and reduced choice for tenants.

"We also need to build more homes given new house building fell to its lowest peacetime levels since the 1920s under the last administration. Our housing initiatives include freeing up disused public land to build more homes, rewarding councils for helping build more homes through a New Homes Bonus."