Haitian President Jovenel Moise was shot dead by unidentified attackers in his private residence overnight in an "inhuman and barbaric act" and his wife was injured, Interim Prime Minister Claude Joseph said on Wednesday.

He said the police and army had the security situation under control but gunshots could be heard throughout the capital after the attack, which occurred amid a rising wave of politically linked violence in the impoverished Caribbean nation.

With Haiti politically divided, and facing a growing humanitarian crisis and shortages of food, there are fears of widespread disorder.

"The President was injured and succumbed to those injuries," Joseph said in an interview with Radio Caraibes.

Port-au-Prince had been suffering an increase in violence as gangs battle one another and police for control of the streets.

The bloodshed is driven by worsening poverty and political instability. Moise faced fierce protests after taking office as president in 2017, with the opposition accusing him this year of seeking to install a dictatorship by overstaying his mandate and becoming more authoritarian - charges he denied.

"All measures are being taken to guarantee the continuity of the state and to protect the nation," Joseph said.