Not enough evidence to pursue alleged Navy sex assaults

AN INVESTIGATION into alleged sexual assaults on the Navy vessel the HMAS Ballarat has found there was "insufficient evidence" to guarantee a conviction in the matter.

A statement from the Department of Defence released on Friday said the Director of Military Prosecutions investigation did not find enough evidence for "a reasonable prospect of conviction".

That inquiry was one of two prompted by allegations of "unacceptable behaviour" on board the HMAS Ballarat, with an administrative inquiry also underway.

The administrative inquiry will now assess whether any "broader procedural or cultural issues" may require further action by the Navy.

While the Defence would not provide any more details, it would confirm that "it continues to treat the matter with the utmost seriousness".

Chief of Navy Vice Admiral Ray Griggs said he remained committed to be "as open and transparent as possible" without compromising the investigations.

"The integrity of the inquiry process remains a critical concern," he said.