The Australian swimming duo, who split soon after they both won medals at the 2008 Olympic Games, took to their Twitter pages to hit back at rumours that they have rekindled the romance.
After various followers alluded to a reunion between the couple, Sullivan wrote on the microblogging site: "Negative.. just bad journalism!" before later adding: "Not true."
Rice then wrote: "Sorry to disappoint... only friends, hey Sullo?"
After Sullivan and Rice ended their two-year relationship in 2008, she was romantically linked to fellow swimmers Nick D'Arcy and Michael Phelps.
She reportedly recently split from rugby union player Quade Cooper after more than a year together.
Sullivan was briefly linked to former Miss Universe Australia Rachael Finch when they both took part in Celebrity MasterChef, but she soon got together with her Dancing with the Stars partner Michael Miziner.
Sullivan was named CLEO magazine's 'Bachelor of the Year' in 2011, beating stars such as ironman Caine Eckstein, DJ Chris Stafford and Neighbours actor Scott McGregor.
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