Charities are concerned that media reports of charity clothing collection scams will reduce people’s willingness to donate items and cost them millions in lost income.
Bogus collectors have recently used the names of the Down’s Syndrome Association and the RNLI, and a BBC report this month exposed a company that claimed to collect for Breakthrough Breast Cancer in Kent.
David Moir, head of policy at the Association of Charity Shops, said the reports of scams could damage public trust.
"It is highly possible that these bogus collectors could harm the public’s confidence in giving clothes to charitable collections, and that will have a damaging affect on charities’ stock levels," he said.
Moir said he planned to meet the Association of Chief Police Officers this week to discuss how they could tackle the problem. "I do understand that they have other priorities, but this problem is not going to go away," he said.
A spokeswoman for the British Heart Foundation, which has 642 stores in the UK, said it would have to spend £3m this year to attract enough donations to maintain stock levels. The charity had spent £2.1m last year to generate donations of clothing, she said, and could spend £6m doing so next year.
The BHF last month said it was also concerned about the greater use by charities that do not have shops of commercial collectors, who sell the clothes for rag and then donate a percentage of the profit they make to the charity.
It pointed out that charities get the full value of clothes they collect or that are taken to shops, while commercial collectors gave a proportion of the value to charity that the Association of Charity Shops had calculated to be as little as 5 per cent.
Jeff Brown, regional operations manager for pet care charity PDSA, which has 180 high street shops, said the proportion of collection bags that came back with donations had dropped from 15 per cent to 8 per cent over the past year because of theft by bogus collectors.
"Members of the public are becoming wiser to this and they may be more reticent about donating, not knowing whether the clothes will be going to charity," he said.
Cancer Research UK, Oxfam and the British Red Cross, which in total run more than 1,500 high street shops, also said they had witnessed a decrease in stock levels over the last two years.
A spokesman for Clothes Aid, a commercial clothing collections firm, said the company had helped the police with more than 190 arrests of bogus clothing collectors over the past two years. The firm has now started training staff to detect theft, he added.