Ryan's alleged fee demands apparently prompted Channel 5's producers to ditch plans to have him in the house.
According to The Sun, UK garage star Romeo was the producers' fourth choice after Tinchy Stryder, Wiley and Ryan.
Romeo previously appeared on Channel 4 reality series The Games.
Michael Madsen, Loose Women actress Denise Welch, X Factor's Frankie Cocozza, Natasha Giggs and Nicola McLean are among the other celebrities rumoured to be taking part in the show.
Celebrity Big Brother starts on January 5 at 9pm on Channel 5.
> Brian Dowling Celebrity Big Brother interview
Look through our gallery of rumoured Celebrity Big Brother 2012 housemates below: