An unknown number of inmates have escaped after armed gangs stormed the main prison in the Haitian capital Port-au-Prince on Saturday evening, according to the French embassy and local media.

"This Saturday evening, bandits stormed the national penitentiary in Port-au-Prince and allowed a number of inmates to escape," the French embassy said in a note sent to AFP.

"Pending clarification of the situation, the embassy of France advises against all travel in the Port-au-Prince metropolitan area," it said.

In a message written in Creole and posted on social media platform X, the Haitian National Police Union SNPH-17 appealed to all police and military personnel with cars, weapons and ammunition to go to the prison as reinforcements.

According to the local online news outlet Gazette Haiti, "a significant number of prisoners released" by the armed gangs are "important members of very powerful gangs."

Known gang leaders and those charged with the 2021 assassination of president Jovenel Moise were among those incarcerated in the prison, located a few hundred meters from the National Palace, the Haitian daily Le Nouvelliste said.

It said it had no details on the number or profile of the prisoners that escaped.

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

Gangs aiming to oust Haitian Prime Minister Ariel Henry have wreaked havoc in Port-au-Prince since Thursday.

Henry is not in the capital, according to Le Nouvelliste.

The latest attacks are part of a coordinated effort by gangs united under the label "Vivre Ensemble" ("Living Together").

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

The Caribbean state was already prey to gang violence but gangs now control 80 percent of Port-au-Prince, and serious crime has reached record levels in the Western hemisphere's poorest nation, according to the United Nations.