Michael Clarke Duncan's former fiancee Omarosa Manigault has vowed to "go after" La Toya Jackson "with a vengeance" if she fails to formally apologise for suggesting the reality Tv star played a part in the actor's death.

The singer was recently fired from Donald Trump's hit U.S. reality show The Celebrity Apprentice and she took aim at her Tv rival Manigault during an exit interview, accusing her of playing a role in his 2012 passing.

Jackson told the cameras, "She's a conniving, scheming, cut-throat (who) probably pulled the cord on Michael Clarke Duncan."

Manigault's attorney filed a defamation lawsuit against the 36 year old on 18 March (13), the day after the episode aired, claiming Jackson's comments were "false" and "vicious".

Jackson appeared to backtrack over her controversial comments as she addressed her ousting during an appearance on U.S. breakfast show Today last Tuesday (19Mar13), insisting she "didn't mean it that way", but now Manigault has threatened to drag Jackson into court if she doesn't properly apologise.

Manigault tells talk show host Wendy Williams she is "sparing no expense" to clear her name, stating, "I got a letter from her attorney... and she blamed everybody. She blamed The Apprentice producers, she blamed her other castmates, she said she was stressed out, but she never apologised...

"She is going to have to come out publicly and she's going to have to retract those statements, or I am going to go after her with a vengeance."

Jackson reportedly has until the end of the work day on Monday (25Mar13) to issue a formal apology or face court action.