The 86-year-old, who cannot be named because that could identify the complainants, pleaded guilty in Warrnambool County Court to three counts of indecent assault and two counts of gross indecency with or in the presence of any girl under 16.

Crown prosecutor Craig McConaghy said the charges related to five incidents between September 1, 1964 and December 31, 1965.

He said at the time of the offending, the man was aged between 31 and 32.

The victims were aged between six and 12.

In a victim impact statement, one of the victim's said enduring the trauma of sexual assault by an adult who was supposed to care for her was incomprehensible.

She said the trauma was printed into her memory and she carried the secret with her for the last 51 years.

"No matter how hard I try, it won't leave me," she said.

"I struggle to understand why you did this to me."

Lawyer Bradley Newton said his client was elderly, had ill health and rapid cognitive decline.

He asked Judge Michael O'Connell to consider a corrections order or suspended jail sentence.

The prosecutor said the maximum penalty for the offences was up to three years in jail.

He said the penalty was relevant to the time of the offending and that the relevant provisions had since changed significantly.

The man will be sentenced on Friday.

Have you signed up to The Standard's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in the south-west.