The widow of slain Haitian President Jovenel Moise, who was critically wounded in an attack that claimed his life, on Saturday issued her first public statement since the assault, calling on the nation not to "lose its way."

Martine Moise delivered the statement in an audio message posted on her official Twitter account three days after her husband was shot dead in their home.

Moise was gunned down at his Port-au-Prince home before dawn on Wednesday by what Haitian authorities said was a unit of trained assassins comprised of 26 Colombians and two Haitian Americans. 

Doubts have grown, though, about that narrative, with families of at least two of the Colombians saying they had been hired as bodyguards. 

Martine Moise, who was wounded in the attack and flown to Florida for medical treatment, said her husband was targeted for political reasons. 

"You know who the president was fighting against," she said in the recording, without naming anybody. 

"They sent mercenaries to kill the president at his home with members of his family because of roads, water, electricity and the referendum as well as elections at the end of the year so that there is no transition in the country," she said. 

Haitian officials have not given a motive for the assassination or explained how the killers got past Moise's security detail. 

The late president had spoken of dark forces at play behind years of unrest under his mandate – rival politicians and oligarchs angry about what he called his attempts to clean up government contracts and politics – and proposed a referendum to change Haiti's constitution. 

The referendum, scheduled for September 26 along with presidential and legislative elections, could abolish the prime minister's position, reshape the legislative branch and strengthen the presidency. Moise's assassination has clouded those plans and led to political disarray in Haiti.

Late on Friday, the man Moise appointed as prime minister just before he was assassinated claimed the right to lead Haiti, pitting him against acting head of state Claude Joseph, whose government has managed the response to the killing to date. 

Ariel Henry, a neurosurgeon who Moise named prime minister on Monday, said he was now the highest authority in Haiti, not interim Prime Minister Joseph, and that he was forming a government. 

"After the president's assassination, I became the highest, legal and regular authority because there was a decree nominating me," he said. 

Henry said his government would create a new electoral council which would determine new dates for elections to be held "as soon as possible." 

But Henry has yet to be sworn in, and Joseph, who was named interim prime minister in April, has stayed put.

The power struggle has created confusion over who is the legitimate leader of the country's 11 million people. 

Elections Minister Mathias Pierre said acting premier Joseph would keep that role until the September 26 vote. 

Meanwhile, Haiti's Senate, which currently comprises just a third of its usual 30 senators, nominated its head Joseph Lambert, on Friday to act as the interim president. 

Haiti's 1987 constitution stipulates the head of the Supreme Court should take over as interim president. But amendments that are not unanimously recognized state that it should be the prime minister, or, in the event that it is the last year of a president's mandate, that parliament should elect a president – as was the case with Moise. 

Further complicating matters, the head of the Supreme Court died last month after contracting COVID-19. 

There also is no sitting parliament, as legislative elections scheduled for late 2019 were postponed amid political unrest. 

(With input from Reuters, AFP)