Haitian officials and reporters say police have detained a prominent attorney who launched corruption cases against the family of President Michel Martelly.
Senate leader Simon Dieuseul Desras has called for an emergency session of legislators to discuss Andre Michel's arrest, which sparked protests in the capital Port-au-Prince on Tuesday.
Michel had initiated legal proceedings against the wife and eldest son of the country's presdent before his detainment.
Reporters for privately owned Radio Caribe say they witnessed police officers detaining the lawyer on Tuesday evening.
Neither police nor prosecutors responded to phone calls seeking confirmation. The reason for the detention was unclear.
Haitian police fired into the air on Tuesday and used tear gas against protesters angry over the arrest of the opposition lawyer.
Protesters responded by throwing rocks at police and setting up flaming barricades in the streets.
"This is a kidnapping. It is a human rights violation. The law establishes the terms under which a person can be arrested," said Newton St-Juste, a lawyer who had joined Michel in filing the legal proceedings against the president's
family on grounds of corruption.
"It is an arbitrary and illegal act. This is a dictatorship," said Pierre Esperance, member of the Human Rights Defense Network.
The speaker of parliament, Jean Tolbert Alexis, called for more protests over Michel's arrest.
"The achievements of our democracy are in jeopardy. We cannot turn back," Alexis said.