Interior Minister Nicolas Sarkozy on Monday defended his tough crime policies against claims they helped increase tension after a fourth night of rioting in a Paris suburb in which tear gas was fired into a mosque. It was not clear who had fired the tear gas and Sarkozy, addressing police officers, vowed to find out what had happened. Youths hurled rocks and set fire to cars in the northeastern Clichy-sous-Bois suburb of the French capital, where many immigrants and poor families live in high-rise housing estates notorious for youth violence. French television said six police officers were hurt ---SNIP---