The pop superstar and French actor confirmed their split earlier this month amid rumours Martinez had slept with several other women. However, Minogue insists Olivier was always faithful - and that there is a chance the couple may reunite at a future date.
She says, "None of the rumours about Olivier cheating are true. I don't believe any of it."
"Olivier and I still care about each other and there's still a lot of love between us. I still speak to Olivier and you never know what will happen in the future."
Minogue is also urging her fans not to badmouth her ex-boyfriend.
She writes on her website: "For someone for whom I have an enormous love and respect, and communicate with, it is so grossly unfair to demonise a honest man."
"I would ask of you, my fans, to show your support for both Oli and myself as a separation is never easy."