U.N. Secretary-General Kofi Annan urged Israel to exercise maximum restraint as its recent military operations in Gaza have killed a number of Palestinian civilians, U.N. spokesman Stephane Dujarric said Friday. Military operations in populated areas inevitably cause civilian casualties, said Dujarric. Annan called on the Israelis to do their utmost to protect civilians and to refrain from further escalating an already grave situation, he told reporters. Annan also asked Palestinian fighters to stop firing rockets against Israeli civilian targets. All concerned should remember that continuing violence is liable to make the search for a just and lasting peace in the region even more difficult, said Dujarric. At least 20 Palestinians and one Israeli solder have been killed since Wednesday.