"These allegations are ALL made up."
McLachlan is currently starring in another production of the Rocky Horror Picture Show in Adelaide.
Whelan Browne also appeared in the Channel Ten program The Wrong Girl alongside McLachlan in 2016 and 2017.
She told the ABC she was dismayed when she learned he had been cast but felt she had to continue to have a civil relationship with him for the sake of her career.
She said his behaviour towards her on that program was appropriate.
But she said during Rocky Horror McLachlan, who played the transvestite Frank N Furter to her Janet, said he indecently assaulted her on stage during a sex scene.
McLachlan said Rocky Horror was a "confrontational musical oozing with sexuality".
"As such, as part of the musical the actors have to perform certain actions, all of which follow from the show itself -- and indeed 'make' the show."
The three women said they had asked the production company, GFO, for an independent investigation into their claims, but that fell through.
In a statement, GFO said managing director John Frost was not available for an interview and the company declined to make any comment on the record.