Moise was shot dead on July 7 when assassins stormed his private residence in the hills above the capital Port-au-Prince. The 53-year old had been governing by decree for more than a year after Haiti failed to hold legislative and municipal elections amid a political gridlock and had faced many calls to step down.

His death has left Haiti in an even deeper constitutional and political crisis as it has only a handful of elected officials nationwide.

Henry, a political moderate and neurosurgeon whom Moise named prime minister just days before his death in an attempt to reduce political tensions, has sought to forge a new consensus between different political factions.

But allegations over his possible involvement in Moise's killing are overshadowing that.

Prosecutor Bed-Ford Claude said last week that phone records showed Henry had twice communicated with a man believed to be the mastermind behind Moise's killing on the night of the crime.

That suspect, a former justice ministry official whom Henry has publicly defended, is now on the run.

Henry dismissed his request to discuss the matter as politicking and did not respond to the allegations.

That prompted Claude to write on Tuesday to the judge overseeing the investigation into Moise's slaying and ask him to charge Henry as a suspect.

He also wrote to Haitian migration services ordering them not to let the prime minister leave the country "due to serious presumption relative to the assassination of the president".

Later on Tuesday, a letter from Henry to Claude dated September 13 emerged in which he said he was firing him for "grave administrative error", without going into detail. In a separate letter dated September 14, he named Frantz Louis Juste to the post.

It remains unclear whether the order actually is valid as Haiti's 1987 constitution mandates that the prosecutor can only be appointed or fired by the president, a position that remains vacant.

Australian Associated Press