The Defence Forces have confirmed that a member of the Naval Service has been moved from his post and is the subject of an investigation into the alleged passing of sensitive information to civilians without authority.
It is understood the alleged breach concerns information about the movement of naval patrol vessels.
Naval Command became aware of the alleged disclosures last summer during regularly conducted security checks.
An investigation was carried out by military police, during which the person under investigation was interviewed.
The investigation concluded at the end of last summer and a file has subsequently been sent to the Director of Military Prosecutions.
He must decide whether or not to bring a case against the individual concerned under the Defence Acts.
In the meantime, the person against whom the allegations have been made continues to serve, but has been removed from the post where the sensitive information was being handled.
Gardaí have also been made aware of the investigation and are participating in it.
The alleged information breach is being treated as extremely serious, because it may have concerned operations by gardaí, the Naval Service and Revenue Customs & Excise to combat the smuggling of drugs, weapons and other contraband in and out of the country.