GAZA CITY -- Israel destroyed the headquarters of Hamas' prime minister and blasted a sprawling network of smuggling tunnels in the southern Gaza Strip Saturday, broadening a blistering 4-day-old offensive against the Islamic militant group even as diplomatic efforts to broker a cease-fire appeared to be gaining steam.
"There are discussions about the ways to bring a cease-fire soon, but there are no guarantees until now," Morsi said at a news conference. He said he was working with Turkey, Arab countries, the United States, Russia and Western European countries to halt the fighting.
Israel launched the operation Wednesday in what it said was an effort to end months of rocket fire out of the Hamas-ruled territory. It began the offensive with an unexpected airstrike that killed Hamas' powerful military chief, and since then has relentlessly targeted suspected rocket launchers and storage sites.
In all, 46 Palestinians, including 15 civilians, have been killed and more than 400 civilians wounded, according to medical officials. Three Israeli civilians have been killed and more than 50 wounded.
Israeli military officials expressed satisfaction with their progress Saturday, claiming they have inflicted heavy damage to Hamas.
"Most of their capabilities have been destroyed," Maj. Gen. Tal Russo, Israel's southern commander, told reporters. Asked whether Israel is ready to send ground troops into Gaza, he said: "Absolutely."
A White House official said President Barack Obama was in touch with the Egyptian and Turkish leaders. The United States has solidly backed Israel so far.
Speaking on Air Force One, deputy national security adviser Ben Rhodes said that the White House thinks Israel "has the right to defend itself" against attack and that the Israelis will make their own decisions about their "military tactics and operations." The White House, like Israel, considers Hamas a terrorist organization.
Despite the bruising offensive, Israel has failed to slow the barrages of rockets from Gaza.
The Israeli military said 160 rockets were launched into Israel Saturday, raising the total number to roughly 500 since this week's fighting began. Eight Israelis, including five civilians, were lightly wounded yesterday, the army said.
Israel carried out at least 300 airstrikes Saturday, the military said, and it broadened its array of targets. One air raid flattened the three-story office building used by Hamas' prime minister, Ismail Haniyeh. He was not inside the building at the time.
In southern Gaza, aircraft went after the tunnels that militants use to smuggle in weapons and other contraband from neighboring Egypt. Tunnel operators said the intensity of the bombing was unprecedented, and that massive explosions could be heard miles away, both in Gaza and in Egypt.
The operators, speaking on condition of anonymity because of the illicit nature of their business, said they cannot approach the tunnel area to assess the damage, but the blasts appeared to be more powerful than in Israel's last major push to destroy the tunnels during a previous offensive four years ago.