At least 30 people are feared to have been killed in a stampede at a popular tourist site in Haiti on Saturday.

The incident took place on Saturday during an annual Easter gathering at the Laferrière Citadel, a Unesco World Heritage site, Jean Henri Petit, head of civil protection for Haiti's Nord department, said, warning the death toll could yet rise.

Prime Minister Alix Didier Fils-Aimé said the incident occurred "during a tourist event attended by many young people" at the site, in the northern town of Milot.

He said an investigation had been launched and "all relevant authorities" mobilised to support those affected.

"The government sends its sincere condolences to the affected families," Fils-Aimé said in a statement.