A renewal of Palestinian rocket attacks has prompted tough talk in Israel's election campaign on Sunday. 

The top Israeli candidates for prime minister have vowed that, if elected, they will topple the Islamic militant group Hamas that rules the Gaza Strip.  The threats came after dozens of Palestinian rockets had been fired at Israel since Friday, when a six-month Gaza ceasefire expired.

Foreign Minister Tzipi Livni hopes to become Israel's first woman prime minister in more than 30 years when elections take place on February 10. Livni, who heads the ruling Kadima political party, said her government's "strategic objective" would be to remove Hamas from power - using military, economic and diplomatic means.

Livni's main opponent, Likud Party member and former Prime Minister Benjamin Netanyahu, made a similar promise when he visited a home that was damaged by a rocket in the hard-hit Israeli town of Sderot.  "In the long-term, we will have to topple the Hamas regime," Netanyahu said.  In the short term, he said there is a wide range of options.  He accused the Kadima government of doing nothing.

In Gaza, Hamas Prime Minister Ismail Haniyeh was unfazed.  "Nothing can destroy our people," he said, adding that Israel was responsible for the collapse of the ceasefire.

Israel is reluctant to invade the heavily-populated Gaza Strip because it fears high casualties among Israeli soldiers and Palestinian civilians, and, in turn, international condemnation.

But with rockets creating havoc in southern Israel, many analysts say it is not a question of whether Israel will launch a major offensive in Gaza, but when.