The Charities Commission says not-for-profit groups are vulnerable to theft and fraud, and has launched a series of workshops for the charities to help them detect and combat it.
In a recent survey by accounting firm BDO, 86% of charities that replied felt fraud was a problem for the sector but only a quarter had controls in place.
Commission chief executive Trevor Garrett says even a small amount of fraud can have a devastating effect on a charity.
Mr Garrett says his advice is to always be open with the public and be able to assure them systems are in place to stop problems happening again.
The workshops will be held around the country this month.