Israel's prime minister says the country's cease-fire in Gaza is "fragile," and that Israel will not hesitate to respond if Hamas continues to launch new attacks.

Prime Minister Ehud Olmert spoke Sunday before the start of a weekly Cabinet meeting, telling reporters the cease-fire is being examined "minute by minute."

Israel declared a unilateral cease-fire to start in the Gaza Strip in the early morning (at 2 a.m. local time (0000 UTC).  But the tense calm was shattered just hours later.

Palestinian militants fired at least six rockets at the southern Israeli town of Sderot, while Israeli troops and Hamas militants clashed in northern Gaza.

The Israeli military says warplanes targeted Hamas rocket launchers used in the attack on Sderot.

Palestinian medical workers say Israeli troops also shot and killed a civilian near the town of Khan Younis, not far from where the rockets had been fired.

Mr. Olmert had announced an end to the Gaza offensive Saturday, saying Israel had achieved all its goals. 

He also said Israeli forces will remain in Gaza while long-term plans are worked out, and that they would respond if attacked.

Meanwhile, the Palestinian death toll from the three-week Israeli offensive is rising. 

Palestinian officials say they have recovered 25 bodies -- including those of children -- from rubble in northern Gaza.  Palestinian health officials said Saturday the fighting killed more than 12-hundred people. 

Many Palestinians are returning to their homes for the first time today to assess the damage.

Hamas spokesman Fawzi Barhoum had said the unilateral cease-fire was not enough to end the militant group's resistance.  The spokesman demanded Israel's complete withdrawal from the territory, the lifting of the blockade and an opening of all of Gaza's border crossings.

Israel says it launched its offensive on December 27 to stop years of militant rocket fire from Gaza into Israel.  Thirteen Israelis, three of them civilians, have died in the conflict.

During his televised address Saturday, Mr. Olmert apologized to the people of Gaza for the heavy civilian casualties inflicted by Israeli forces, and said Israel would help with humanitarian and recovery efforts.


Some information for this report was provided by AFP, AP and Reuters.