Regional officials said a synagogue in northern France has been vandalized, its facade sprayed with graffiti that included a swastika. The administration for the Nord region said the vandals struck the synagogue in Lille on Tuesday. An investigation has been opened, but no one has been detained. France has Western Europe's largest Jewish and Muslim communities, and a history of ethnic tension when hostilities in the Middle East are high. The country has seen a spate of incidents like Tuesday's since the start more than two weeks ago of Israel's offensive in Gaza. French President Nicolas Sarkozy on Wednesday promised a policy of "zero tolerance" against those who commit anti-Semitic or anti-Muslim crimes.