CARACAS, Venezuela -- Hundreds of Venezuelan police and National Guard troops broke up an opposition march in the capital Friday with volleys of tear gas and water cannon blasts.
Thousands of opponents of President Hugo Chavez retreated as clouds of gas spread out over an avenue in downtown Caracas.
City health official Ivon Lamprea said at least 15 people suffered minor injuries, including a police officer whose hand was injured and a protester who was hit in the face by an object. She said the rest were treated for inhaling tear gas.
National Guard Gen. Alirio Ramirez, said protesters had not been given permission to march past officers to the National Assembly or the city center and that authorities broke up the demonstration to maintain order.
People in surrounding buildings hurled glass bottles at officers, and some beat on pots and pans to protest the police response.
Police pursued demonstrators into side streets, including one group of several dozen who sat down in protest. Caracas Mayor Antonio Ledezma, a leading Chavez opponent, rose and raised a copy of the constitution above his head before police dispersed them by spraying water and tear gas.
"This is a confirmation of faith in ourselves, in our ability to fight," Ledezma said earlier.
The violence broke out as thousands of opponents and supporters of Chavez held separate May Day marches in the Venezuelan capital.
Opposition protesters said they were there to support Ledezma and other anti-Chavez leaders who they say have been sidelined through targeted corruption probes and laws that limit their power.
Many carried signs picturing opposition leader Manuel Rosales, who earlier this week obtained political asylum in Peru.
The government denies persecuting opponents and says Rosales should be brought to trial on a corruption charge.
Chavez blamed the violence on the protesters and said the authorities were obliged to disperse them.
"We won't permit this violence," he told a crowd of supporters. "That wasn't a march of workers, but a march of conspirators."