An RNLI employee has been arrested and bailed on suspicion of fraud after the charity raised concerns with the police.
A spokeswoman for Dorset Police said that the RNLI initially made a complaint of fraud to Action Fraud, the UK’s national fraud and internet crime reporting centre. This was referred to Dorset Police on 8 May.
The spokeswoman said: "As a result of the investigation, a 53-year-old man from the Wareham area was arrested on suspicion of fraud and has been released on police bail until the middle of March, 2015."
A statement emailed to RNLI staff, which has its headquarters in Poole, Dorset, said the organisation was "taking the matter very seriously" and conducting an internal investigation as well as working with the police.
The statement said: "To the best of the RNLI’s knowledge at this time, the allegations that have been made are in relation to an isolated incident and relate to a single member of the organisation."
The spokeswoman said she was unable to comment further because of the police investigation.
According to Action Fraud, police forces in England and Wales recorded 270 reports of alleged charity fraud in the final three months of 2013. This was the first time that such data had been collected at a national level.
A spokeswoman for the Charity Commission said: "I can confirm that the commission received a serious incident report from the charity in connection with a suspected fraud. We are satisfied that the trustees are responding appropriately to the incident and have asked to be kept informed. In the meantime, we have no regulatory concerns."