Six police stations that the group RNDDH visited in Haiti's Ouest Department showed "very alarming" conditions, it said, urging immediate action from the judicial system, which has struggled for years and is facing strikes by staff calling for better work conditions.

In the Port-au-Prince police commissariat, RNDDH said, 92 prisoners were being kept in two "filthy" cells, intended for just 10 people each for a maximum of 48 hours ahead of court hearings - though many detainees had been held for months.

"These people are kept in inhumane, degrading conditions, in filthy, cramped and nauseating detention centers converted into prisons, despite the fact that they were neither built nor equipped for this purpose," RNDDH said.

Haiti's prosecutors' office and national police did not immediately respond to a request for comment.

The rights group said many of the detainees in the Port-au Prince station had received no visits, reducing their access to food and water normally brought by relatives.

The commissariat held 38 women, it said, some of whom slept in the chief's office overnight under police supervision, where other detainees were permitted "a breather" during the day.

RNDDH said one woman detained there had been eight months pregnant in November, when she suffered a medical issue at the station and was taken to hospital for further tests, which found her child had died and her life was at risk.

Another woman, six months pregnant, had not been examined since her January arrest, it added.

While staff were trying to transfer detainees out of the station, RNDDH said, many men were awaiting hearings or court orders and the planned transfer of women had been delayed by overcrowding at other prisons and attacks by gangs.

Between January and April last year, the United Nations documented 54 deaths due to malnutrition in Haitian prisons.

Haiti has seen an escalation in violence by armed gangs, driving a humanitarian crisis that has displaced tens of thousands of people.