Haiti's government has declared a state of emergency and nighttime curfew in a bid to regain control of the country after a deadly gang assault on the capital's main prison that allowed thousands of inmates to escape.

The curfew will be enforced from 6 pm to 5 am in the Ouest region, which includes the capital, through Wednesday, the government said in a statement on Sunday, adding that both the curfew and the state of emergency can be extended.  

About a dozen people died as gang members attacked the National Penitentiary in Port-au-Prince overnight Saturday into Sunday, an AFP reporter observed.

The attack came as part of a new spate of extreme violence in the Haitian capital, where well-armed gangs who control much of the city have wreaked havoc since Thursday.

This screen grab taken from AFPTV shows people looking at the building of the main prison of Port-au-Prince. Photo: AFP

The gangs say they want to oust Prime Minister Ariel Henry, who has led the crisis-wracked Caribbean nation since the assassination of president Jovenel Moise in 2021.

Only around 100 of the National Penitentiary's estimated 3,800 inmates were still inside the facility Sunday after the gang assault, Pierre Esperance of the National Network for Defense of Human Rights said.

"We counted many prisoners' bodies," he added.

An AFP reporter who visited the prison on Sunday observed around a dozen bodies outside it and hardly anyone inside. Some bodies had wounds from bullets or other projectiles.

In its statement late Sunday, the Haitian government said security forces had "received orders to use all legal means at their disposal to enforce the curfew and detain those who violate it."

It said the objective was to allow the government to "re-establish order and take the appropriate measures to take back control of the situation."

Economy Minister Patrick Michel Boisvert signed the statement as the country's acting prime minister.

Prime Minister Henry was in Kenya last week to sign an agreement to deploy police from the East African country to lead a UN-backed law and order mission to the gang-plagued nation.

Haiti's government is notoriously weak -- kidnapping and other violent crime is rampant and gangs are described as much better armed than the police themselves.

Gang members also attacked a second prison called Croix des Bouquets, police said earlier.

Known gang leaders and people charged in the assassination of Moise were among those incarcerated in the main prison, located a few hundred meters from the National Palace, the Haitian daily Le Nouvelliste said.

The prison had been "spied on by the assailants since Thursday via drones," before it was attacked early Saturday evening, according to Le Nouvelliste. 

Esperance said it was not immediately clear how many inmates escaped from the second prison, which he said held 1,450 inmates.

Kenya-led security mission

Powerful gang leader Jimmy Cherisier, known by the nickname Barbecue, said in a video posted on social media that armed groups in Haiti were acting in concert "to get Prime Minister Ariel Henry to step down."

It was not immediately clear on Sunday if the prime minister had returned to Haiti after his Kenya trip. 

The UN Security Council in October approved an international police support mission to Haiti that Nairobi had agreed to lead, but a Kenyan court ruling has thrown its future into doubt.

On Friday, Henry signed an accord in Nairobi with Kenyan President William Ruto on deploying the force.

Haiti prime minister Ariel Henry had travelled abroad at the time of the jail break. Photo: AFP

Ruto said he and Henry had "discussed the next steps to enable the fast-tracking of the deployment," but it was not immediately clear whether the agreement would counter a court ruling in January that branded the deployment "illegal."

Haiti, the Western hemisphere's poorest nation, has been in turmoil for years, and the 2021 presidential assassination plunged the country further into chaos.

No elections have taken place since 2016 and the presidency remains vacant.

Protesters have demanded Henry's resignation in line with a political deal that required Haiti to hold polls and for him to cede power to newly elected officials by February 7 of this year.