NEW YORK (CNNMoney.com) - Real-estate mogul Donald Trump and domestic diva Martha Stewart fired back at each other in a prime-time-worthy battle of words.

"If I'd had my druthers, there would have been only one 'Apprentice' on the air at one time," Stewart recently told Newsweek magazine.

"The Apprentice: Martha Stewart," NBC's much-hyped new version of the popular reality show launched with Donald Trump, suffered lackluster ratings.

In an interview, she said that having both versions of "The Apprentice" air during the same season was "unfair" but added that "Donald really wanted to stay on."

Stewart said that she was supposed to start out her new show by firing Trump, so that hers would be the only version of "The Apprentice" left on the air.

Trump shot back in a published letter to Stewart on Tuesday, calling her a liar. "Essentially, you made this firing up just as you made up your sell order of ImClone," he wrote. Stewart was convicted of lying about her sale of ImClone Systems Inc. (Research) stock and served five months in prison.

Trump also wrote: "Your performance was terrible in that the show lacked mood, temperament and just about everything a show needs for success."

"I knew it would fail as soon as I first saw it -- and your low ratings bore me out."

In a statement issued late Tuesday, Stewart said Trump's "letter is so mean-spirited and reckless that I almost can't believe my longtime friend Donald Trump wrote it."

NBC had high hopes for its Martha Stewart version of "The Apprentice" but the network announced that it will not produce another season. Ratings for the original Donald Trump "Apprentice," also fell off dramatically last season.

Reuters contributed to this report.

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