Tunisian police fired warning shots to disperse radical Islamist protesters after they set a security post ablaze and ransacked an art exhibit they called offensive to Islam.

Seven police officers have been injured and 90 people arrested in unrest since Sunday in three suburbs of the capital, Tunis, Interior Ministry spokesman Lotfi Hidouri said Tuesday.

The latest violence focused on the art exhibit, but reflects larger tensions between secular movements and ultraconservative Muslims known as Salafis. Tunisia is where the Arab Spring pro-democracy uprisings began when protesters overthrew a longtime secular dictator last year. The country now has a moderate Islamist government, and radical Islam has flourished on the fringes amid newfound religious freedoms.

Late Sunday, hundreds of extremists destroyed artworks at an exhibit in the suburb of La Marsa that included paintings that caricatured Mecca, portrayed a nude woman, and showed the word "Allah" spelled with strings of ants.

The next night, radical protesters set fire to a police post in La Marsa and to a security kiosk in Kram. An Associated Press reporter witnessed some of the violence and the damage. Police fired warning shots to disperse them, witnesses said.

In the poor suburb of Sijoumi, Salafi protesters set fire to a courthouse and a security vehicle and looted stores, according to private radio station Mosaique FM.