He also confessed to wearing medals during Anzac Day marches between 2006 and 2008 which falsely indicated he had served in Vietnam.

Mr Cooper, who served in the Royal Australian Army in Malaysia and Borneo during the Indonesian Confrontation between 1964 and 1967, became the subject of an RSL investigation this year.

He said he intended to admit his guilt at an RSL tribunal next month. Under the Defence Act, it is an offence to impersonate a veteran or engage in the improper use of service medals.

Mr Cooper faces the possibility of a lifetime ban from the RSL. If the matter is referred to Australian Federal Police and the Department for Veterans' Affairs, he could be fined up to $3000, jailed for up to six months, or both.

Mr Cooper said he "should have known better" than to wear the medals on the left-hand side of his jacket, which is reserved for decorations earned by the wearer. But he claimed there were mitigating circumstances.

He said the replica medals had belonged to a now-deceased friend who had served in Vietnam.

He said the medals, which he had originally intended to wear correctly in honour of his fallen mates, had become mixed up with his after a botched mounting.

"This is a confession. Yes I was wrong. I was actually at 6th Battalion before I went to Malaya and Borneo, and a lot of my mates (from 6th Battalion) died at Long Tan, and I thought 'damn it, I'm going to wear it for them'," he said. "I should have worn them on the right-hand side (of my jacket), and I feel very ashamed about that."

RSL WA branch president Bill Gaynor said he was glad Mr Cooper had come clean but was disappointed about the deception. The WA president of the Vietnam Veterans' Association, Richard Williams, said the community needed to be made aware of the transgression to discourage Mr Cooper from repeating the offence.

The RSL is investigating another alleged impostor veteran described as a high-profile identity from Perth's south-western suburbs.