Charity shops are being forced into stepping up security after a surge in thefts which have been condemned as an attack on the sick and vulnerable.

In one of the latest incidents, a furious Cromer manager tried to shame a thief by posting a notice in her charity shop window giving details of the crime and its impact.

Thieves have walked out of a range of charity shops wearing clothes taken from hangers, stolen shoes and bags, stuffed their shopping baskets with display goods and used distraction techniques to steal more valuable items.

North Norfolk-based Break, one of the county's major charities, says it now has to use the same security measures as high-street chains in a bid to keep a step ahead of thieves.

And at Cromer's Cancer Research UK shop, manager Sarah Stanforth said she had reached the end of her tether recently when a statue of a cat, priced at �10, was stolen.

She posted a notice to the thief in the Church Street shop's window saying: 'I hope you get pleasure knowing you have taken vital funds from life-saving research.'

The shop had already introduced a ticket system so that staff knew how many articles customers were taking into the changing room and would be installing CCTV, said Mrs Stanforth

'I was so angry. We get so much theft. I've been here six-and-a-half years and it's getting worse,' she added. 'It shouldn't be like this. It's frustrating when you think of where that money should have gone.'

News of the cat statue theft had so appalled charity shop supporters that three well-wishers had each donated �10 to make up the loss and others had brought in extra goods to sell, according to Mrs Stanforth.

She added: 'People were very upset. They know why we're here and how much we rely on their support.'

At the neighbouring Sue Ryder charity shop, manageress Laura Mackay said that very afternoon a brand-new ornamental pill box, worth �3.99, which had been displayed on top of its gift box, had been taken.

Ms Mackay, who has been at the shop for 11 years, recalled watching an elderly woman at Christmas one year loading her basket with glass angels from a display. 'I turned away and when I looked back she had disappeared out of the shop with them,' she said.

'You notice the distinctive things – who knows how much else disappears? We try to keep valuable things near the till but thieves will try and attract your attention and while you're helping them, an accomplice will take them.'

At another Sue Ryder branch an electric guitar was stolen from the window display, according to Ms Mackay. She said charity shops in Cromer used an informal alert system where they would ring each other when suspect customers left their shop. Sue Ryder supports people with terminal and long-term serious illness.

Sue Moulding, who manages Cromer's Break shop, on Hamilton Road, said she had also noticed a rise in shoplifting.

'Sometimes you only realise because of an empty hanger or a space on the shoe rack,' she said.

A Break spokesman said the charity, which is due to open its 39th shop today, at Long Stratton, believed theft from its shops across East Anglia and the West Country was definitely increasing. Charity shops were seen as easy targets because they relied on volunteers, many of whom only worked for a few hours at a time.

Staff had now started taking DVDs out of their boxes, and only displaying one shoe or boot, like high-street stores.

Break's shops, which have a combined annual turnover of �2.3m, made a major contribution towards the charity's work in providing holidays and respite care for vulnerable children, adults and families, said the spokesman.

Theft could also have an added impact on funding because some donors had signed up to the Gift Aid scheme which meant Break got an extra 25pc on top of the sale price of their donated items.

'If something's stolen before we can sell it, we don't benefit from that extra money,' she added.