Rock giants U2 called off a concert planned for Saturday night in St Louis, Missouri as the US city braced for a second day of protests.

:: Rock giants U2 called off a concert planned for Saturday night in St Louis, Missouri as the US city braced for a second day of protests over the acquittal of a former police officer in the shooting death of a black man.

The Irish rock band and entertainment firm Live Nation announced the show’s cancellation in a statement citing concerns about their fans’ security.

“We have been informed by the St. Louis Police Department that they are not in a position to provide the standard protection for our audience as would be expected for an event of this size,” they said.

“We cannot in good conscience risk our fans’ safety by proceeding with tonight’s concert. As much as we regret having to cancel, we feel it is the only acceptable course of action in the current environment.”

A judge in the Missouri city Friday found a white former police officer, Jason Stockley, not guilty of murdering Anthony Lamar Smith, a suspected drug dealer, following a high-speed chase in 2011.

The Lamar Smith case has drawn intense attention in St Louis, where racial tensions have been high since the 2014 killing of a black man in the city’s suburb of Ferguson by a white police officer.

Hundreds of people turned out for initially peaceful protests after the verdict, but the situation turned violent Friday night leading police to break up the crowd with tear gas.

Ten officers were injured in the standoff with rock-throwing protesters, according to St. Louis police who made at least 23 arrests.

More protests were expected on Saturday.