(A riot policeman (L) kicks back a tear gas canister during clashes with protesters in the Ettadhamen district of the capital Tunis June 12, 2012. REUTERS/Zoubeir Souissi )

Hundreds of Salafi Islamists, angered by an art exhibition they say insults Muslims, clashed with police in Tunis on Tuesday, raising religious tensions in the home of the Arab Spring and piling pressure on the moderate Islamist government.

Protesters hurled petrol bombs at officers in some of the worst confrontations since last year’s revolt ousted President Zine al-Abidine Ben Ali and launched uprisings across the Arab world. Salafis, who follow a puritanical interpretation of Islam, blocked streets and set tyres alight in the working class Ettadamen and Sidi Hussein districts of the capital overnight.

By morning, protests had spread to a number of residential districts. Stone-throwing youths stopped trams from passing through the capital’s Intilaqa district where demonstrators entered mosques and used the loudspeakers to call on Tunisians to defend Islam.

An interior ministry official on Tunisian state TV said 97 people had been detained during the unrest, including dozens of Salafis and some “criminals”.