Papua New Guinea's Trade Union Congress says the Prime Minister has until the end of the week to meet its demands over the Julian Moti saga.
The union has condemned Sir Michael Somare over his handling of the saga, and his attempts to thwart the Defence Force inquiry into Mr Moti's escape from PNG last October.
Last week it threatened a nationwide strike after Sir Michael sacked his Defence Minister after he revealed that the Prime Minister had forced him to disband the inquiry.
The Union secretary-general, John Paska, says their ultimatum remains clear that Sir Michael either resigns or recommissions a fresh inquiry.
Mr Paska is concerned that as the acting defence minister, Sir Michael has ordered that he be presented with an edited version of the inquiry's findings by the end of the week.
"This is one of the reasons why we want him to step aside from there also because quite clearly impartiality will not be in place, and it will have the effect of compromising the contents, if you like, of the report, the authenticity of the report."