GAZA CITY, Gaza Strip — Guerrillas in Lebanon rocketed northern Israel today for the second time in a week, drawing Israeli artillery fire and threatening to drag the Jewish state into a second front as it battled Hamas in the Gaza Strip.

The violence defied a new call from the U.N. chief to immediately end fighting in Gaza.

Israel showed no signs of slowing its bruising 19-day-old offensive against Gaza's Hamas rulers, striking some 60 targets in the strip bordering southern Israel. One airstrike hit a cemetery, spreading body parts and rotting flesh over a wide area. The army said the airstrike targeted a weapons cache near the graveyard.

The rocket fire from Lebanon caused no injuries, but sent residents scurrying to bomb shelters. There was no immediate claim of responsibility. Hezbollah, the Iranian-backed guerrilla group that fought a monthlong war with Israel in 2006, denied involvement in last week's attack, and speculation focused on small Palestinian groups.

Lebanese security officials said the Israeli army fired at least eight artillery shells on south Lebanon in response.

The Israeli military said it targeted the source of the rockets, and that it regarded the Lebanese government and military responsible for preventing attacks on Israel. The government of Lebanese Prime Minister Fuad Saniora condemned the attack.