The former Miss Wales brought up her feud with McLean in a Twitter post on Friday (January 6) in which she also lashed out at Natasha Giggs, who like her was revealed to have had an affair with footballer Ryan Giggs during last year's super injunction saga.
"Just watching cbb catch up," she wrote. "Wag' Nicola McLean is a fake. And as for the other one..."
Thomas, a former contestant on the regular edition of Big Brother, has since returned to the social networking site to explain her remarks.
"I've not slammed any1," she insisted. "I called nicola a fake (which is true) Slags off every celeb then comes face 2 face and doesn't say anythin! #strange.
"Yet she had her 'hubby' to corner me @ an event and threaten me. Bearing in mind she slagged me off 1ST and I was just replying #nasty."
Thomas concluded: "Why should I let these 'so called celebs' slag me off & not say anythin? I will stick up for myself 'when I can'! #regardlessofaninjunction."
Nicola and Natasha had a Twitter spat of their own prior to entering Celebrity Big Brother last Thursday (January 5), but have so far been civil to each other in the house.