Many homeless people say they cannot earn enough to rent

St Mungo's annual survey of homeless people revealed that 5% had had some sort of job, but in 1986 it was 86%.

About 60% said they could not earn enough to be able to rent while half said they could not get a job without a permanent mailing address.

The government said measures such as work placements and training were being used to help people back to work.

The survey also showed that homeless people would ideally like to work in IT, construction and the leisure industry and the majority had held down regular work before becoming homeless.

Exact figures unknown

The exact number of homeless people in London is not known, but about 20,000 people live in premises for the homeless.

This does not include people in bed and breakfast accommodation and squats. One in 10 people sleeping rough are women and one in four are over 50, according to the charity.

A spokesman for the Office for the Deputy Prime Minister said its homelessness strategy included measures to help people back to work.

"This includes work placements in the private sector to develop new skills and improving hostels to offer training, support and learning programmes," she said.

"And [we are] testing a new approach where local authorities pay part of a families' rent to allow them to break away from the benefits trap."