Sao Paulo - Clashes between thousands of striking Civil Police officers and elite anti-riot police forces have left more than 30 people injured in Brazil's financial capital of Sao Paulo.

Rubber bullets and tear gas were used Thursday night to break up the clashes, which continued for several hours in a posh Sao Paulo neighbourhood and caused traffic disruptions, media reports said.

Civil Police in Sao Paulo state have been on strike for a month, demanding a 15-per-cent pay raise.

On Thursday, they had sought to march to the office of Governor Jose Serra to press their demands. The clashes broke out when they tried to push past barriers to Bandeirantes Palace, which they were unable to reach.

Among the injured was a television cameraman, but there were no serious injuries, doctors said.

Serra charged that taking part in the demonstration were not only Civil Police officers but also members of unions and the opposition who were seeking to "exploit" the protests for political purposes.

"People cannot carry weapons to a demonstration that are meant to be used to fight criminals," the governor said. "An armed movement is illegal."

A spokesman for the striking Civil Police denied his accusations that the strikers were armed while the CUT, an umbrella organization for unions, said the governor was telling lies to the public and charged him with being responsible for the unrest.

The Civil Police are responsible for criminal investigations while the anti-riot police were part of the Military Police, who are charged with maintaining law and order. (dpa)