Papua New Guinea's former attorney-general says Peter O'Neill's attempt to explain a crucial letter in a corruption case undermines the prime minister's later claim that the letter was forged.
Mr O'Neill has confirmed to the ABC that he signed a letter in 2013 that clarified the intent of an earlier directive to process legal bills, but insists he misunderstood what he was signing.
Mr O'Neill says his chief of staff, Isaac Lupari, drafted the letter for him to sign but Mr Lupari has refused to confirm that he was the author.
"If [Mr O'Neill] says that he didn't sign the first letter, then how is it that in the second letter he refers to the first letter by date?" former attorney-general Kerenga Kua said.
Mr Kua was dismissed for questioning Mr O'Neill's leadership but remains an MP for Sinasina-Yonggamugl.
A legal and political scandal has raged in PNG since police served Mr O'Neill with an arrest warrant for official corruption on June 16.