The Charity Commission has launched a mobile version of its website to help people identify fraudulent charity collectors over Christmas.
The site, which is designed specifically for mobile phones, will allow people who are approached on the street for donations to check whether an organisation is a registered charity.
They will also be able to see what the charity does and find its contact details.
Dame Suzi Leather, chair of the commission, said: "In addition to double-checking details of street charity collections, I would also encourage people who make donations to watch out for email scams and fake websites."
The National Fraud Authority estimated in January 2011 that fraud costs the voluntary sector £1.3bn a year, the equivalent of 2.4 per cent of its total income.