Security forces inspect the site after an attack at the residence of Haiti's president Jovenel Moise in Port-au-Prince, Haiti on Wednesday. Photo: VCG

One of Haiti's most powerful gang leaders said on Saturday his men would take to the streets to protest the assassination of president Jovenel Moise, threatening to pitch the impoverished Caribbean country deeper into chaos.

Jimmy Cherizier, a former cop known as Barbecue who heads the so-called G9 federation of nine gangs, rallied against police and opposition politicians whom he accused of colluding with the "stinking bourgeoisie" to "sacrifice" Moise this week.

"It was a national and international conspiracy against the Haitian people," he said in a video address, dressed in khaki military fatigues and sitting in front of a Haitian flag.

"We tell all bases to mobilize, to mobilize and take to the streets for light to be shed on the president's assassination."

Moise was gunned down before dawn on Wednesday at his Port-au-Prince home by what Haitian authorities said was a unit of trained assassins comprising 26 Colombians and two Haitian Americans. The murder and the still murky plot behind it has caused further political instability in the long-troubled country, prompting the government to call for US and UN assistance.

Cherizier said his followers would practice "legitimate violence" and that it was time for "the masters of the system" - business magnates of Syrian and Lebanese descent who dominate parts of the economy - to "give back" the country.

"It's time for Black people with kinky hair like us to own supermarkets, to have car dealerships and own banks," he said.

Some of the magnates had been at loggerheads with Moise.

Fears of worsening clashes had citizens on edge in Port-au-Prince, which has been racked by violence for weeks as gang members battled police for control of the streets.

"They really don't have the capacity to handle security," city resident Benoit Jean said. "There aren't enough cops."

Tension has been fanned by questions about the government's account of Moise's killing, with families of at least two of the Colombians saying they had been hired as bodyguards. 

None of Moise's guards were injured in the attack, Mathias Pierre, the elections minister, told Reuters.