Just hours after announcing personnel from HMAS Albatross would break with a 30-year tradition and not march at the dawn service due to safety concerns, the defence force reversed their decision.

It is understood an occupational health and safety issue was the reason for the original ban, with personnel not allowed to march in the dark due to safety concerns.

Questioned over the decision in senate estimates hearings on Wednesday afternoon Chief of Navy Vice-Admiral Michael Noonan said personnel would be marching at the Greenwell Point dawn service.

"There was discussion between the Nowra RSL Club and the CO of Albatross earlier this week regarding the Anzac Day march and there were safety concerns for people marching in the dark," he said.

"The potential for slippage.

"There has been subsequent dialogue between Albatross and the RSL and they have come to an arrangement where the people form HMAS Albatross will march on Anzac Day, prior to sunrise.

"We will take sufficient safety mitigations prior to that activity to make sure they don't slip."

VADM Noonan said it was "fair concern" by the CO of Albatross with respect to the "safety of the people".

"We've reviewed the decision and we will take necessary arrangements so the march can go ahead."

VADM Noonan said he was unaware of any problems in the past which might have led to the situation.

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"I don't know on the basis of what historical concerns there might have been, but I backed the decision," he said.

He admitted Nowra and Albatross were closely linked and said there would be no backing away from Anzac Day activities in the Shoalhaven and it will go ahead.

"It's not wide spread that navy personnel march prior to the dawn service around the country," he said.

"This would be a local arrangement and the commanding officer has been in dialogue with the local RSL and has reviewed the decision."

Chief of Defence, General Angus Campbell actually praised Albatross CO Captain Fiona Sneath on her decision.

He said to his knowledge he was unaware of marching associated with the pre-dawn services around the country.

"I'm not criticising the Nowra RSL if they want to march but I do commend the commanding officer to bring the point to attention that we ought to be confident that we are not asking our people who have to concentrate on their music and on their marching in the dark that it's done safely," Gen Campbell said.

"Otherwise there would be an article in the newspaper the following day criticising the navy for putting the safety of its own people and the public at risk.

"Well done to the CO of Nowra and it looks like it's going to be a happy Anzac Day all around."

Defence has denied suggestions the initial move was due to security concerns in the light of the recent Christchurch mosque massacre.