Income in UK charity shops totalled almost £1bn in the most recent financial year, figures from the Charity Retail Association show.
The organisation said total income rose to a record high of £974m in 2011/12, up from £940m in the previous year.
But charity shops are struggling to keep up with demand, the CRA said.
A consumer study, commissioned by the CRA and also released today, found that 22 per cent of 1,822 people surveyed said they were shopping in charity shops more now than two years ago. Nearly one million more people from middle class groups were shopping in charity shops compared with June last year, the CRA said.
The CRA has launched a nationwide campaign in response aimed at boosting donations to charity shops.
Members of the CRA, from large charities such as Cancer Research UK and Barnardo’s to hundreds of local hospices and smaller charities, are supporting the drive, Choose Charity Shops, which runs from today until Saturday. Some 6,000 shops in total are taking part, the CRA said.Wendy Mitchell, head of policy and public affairs at the CRA, said the rise in customers had left charity shops struggling to meet increased demand. The shops are also facing more competition, she said.
"It is more of a struggle at the moment," she said. "Charity shops are finding more competition from cash-for-clothes collections, the for-profit organisations that are collecting.
"In our survey we found that one in six people had started selling their unwanted clothes because of the recession and people were holding on to stuff for longer. There is more competition for stock, but there is still plenty out there."
The CRA said most people had at least one bag of unused clothing in their wardrobes and these items could add £200m of annual income to charity shops.