JERUSALEM - Israeli political and military leaders issued dire warnings yesterday to Hamas that they soon would move against the Palestinian extremist group that controls the Gaza Strip unless renewed rocket and mortar fire against southern Israeli towns is halted.

A surge in airborne attacks from Gaza has followed last week's termination of a six-month truce and is fueling speculation that Israel might try to topple Hamas.

"We will not accept this situation," Defense Minister Ehud Barak said yesterday. "Whoever harms the citizens and soldiers of Israel will pay a heavy price."

Despite concerns that a military invasion of Gaza would be complicated, bloody, and not assured of success, Israeli leaders maintain that all options are under consideration.

Army chief of staff Gabi Ashkenazi told a graduating class of flight school cadets yesterday that Israel "will need to use all its force in order to damage terror infrastructure and create a different and safe reality in the Gaza vicinity."

Hamas leaders declared an end to the truce last week, after six months of relative calm on Israel's southern flank.

In a clear show of firepower, extremists launched at least 60 makeshift rockets and mortar shells toward Israel on Wednesday, causing panic in several towns but no serious injuries. About five rockets were launched yesterday, according to the Israeli army.

Hamas won Palestinian parliamentary elections in January 2006 and took full military control of Gaza in clashes with its rival, Fatah, in summer 2007. Fatah, which is supported by Israel and the United States, now controls only the West Bank.

Egypt, which helped broker the recent truce, continued to offer mediation. President Hosni Mubarak called for restraint by both sides yesterday after meeting with Israeli Foreign Minister Tzipi Livni in Cairo.

Livni made clear that Israel would make its own decisions regarding what to do about Gaza.

"With all due respect to Egypt, I didn't come here to get permission for a military operation," she said.

Israeli Prime Minister Ehud Olmert, who is stepping down, took a slightly different approach yesterday, sitting for an interview with the Arab satellite news channel al-Arabiya and calling for residents of Gaza to topple Hamas themselves.

"Stop them. Stop your enemy and ours," Olmert said, according to a statement released by the prime minister's office. "Is the spirit of Islam to kill innocent children, to fire rockets at kindergartens and civilians? I don't think that is the spirit of Islam."

Al-Arabiya broadcast selected excerpts from the interview, which will be shown in full today. In them, Olmert renewed his recent calls for "complete peace with open borders" with Israel's Arab neighbors. He also endorsed the creation of an independent Palestinian state using the 1967 borders as "the main source" for its final shape.