Protesters have burned tyres and thrown rocks and glass bottles at riot police during another anti-government demonstration in Haiti's capital amid a political stalemate over long-delayed elections.

The demonstration of mostly young men reached a peak of about 1,500 in downtown Port-au-Prince as protesters called for the departure of President Michel Martelly.

Police fired tear gas and sprayed water from an armoured vehicle, scattering the crowd at a plaza close to where the National Palace stood before it collapsed in Haiti's 2010 earthquake.

There has been no let-up in protests since last month's resignation of Martelly's prime minister, Laurent Lamothe, and other concessions aimed at resolving the stalemate holding up legislative elections.

A presidential commission had called for Lamothe's resignation, among other steps, to resolve the gridlock that has sparked protests.

After fleeing a blast from a water cannon, protester Jean Junior said Martelly had to go. "Haiti cannot continue like this because the population has not benefited from this government," he told The Associated Press.

Haiti faces an uncertain political future in the coming days with Senate seats expiring Monday, exactly five years after a devastating earthquake struck the nation of 10 million people. If a last-minute agreement is not reached through negotiations with opposition lawmakers, Martelly will rule by decree starting next week.

Martelly was supposed to call elections in 2011 for a majority of Senate seats, the entire Chamber of Deputies and local offices. But opposition senators have lately used parliamentary procedure to prevent the ballots while accusing the president of abusing his authority to appoint supporters to the electoral council.