The government has been warned not to "sweep away" safety nets preventing people from falling into homelessness, as a charity revealed the number of people sleeping rough on the streets of London has risen by just under 50%.

Crisis highlighted figures covering England showing that the number of people sleeping rough increased by 23% between autumn 2010 and autumn 2011 to reach more than 2,000.

The charity said this was the most dramatic growth seen since the 1990s and it urged the government to put an end to suggestions that housing benefit could be withdrawn for the under-25s.

The findings were based on research from Heriot-Watt University and the University of York using various studies, including one which found that there has been a 43% rise in recorded rough sleeping in London over the past year.

The number of households accepted as statutorily homeless in England rose from 40,020 in 2009/10 to 50,290 in 2011/12, the research said.

The findings also highlighted a "concerning" rise in the numbers of households with children in bed and breakfast hotel placements, from 630 in March 2010 to 1,660 in March 2012.

Leslie Morphy, chief executive of Crisis, said: "The coalition is sweeping away the safety nets that have traditionally saved people from the horrors of homelessness.

"Housing benefit, the duties of local councils and the security and availability of social housing are all being cut back.

"Young people are already bearing a disproportionate burden of the cuts and economic downturn, yet the government seems set to increase the pressure by abolishing housing benefit for under-25s."

Releasing its findings ahead of the autumn Statement tomorrow, the charity said that "hidden homelessness" is rising.

It said overcrowding has increased markedly since 2003, from 2.4% to 3% of all households - equating to some 670,000 households in England.

Crisis called for the government to plough more investment into new social and affordable housing and to improve standards in the private rental sector, which has seen rents soar amid strong demand from "trapped" tenants who are unable to meet lenders' toughened criteria to buy a house.