Defense Minster Ehud Barak on Friday blamed Hamas for the escalating violence in the south, and said the Islamic movement would bear the consequences of it.

"Hamas is directly responsible for the current situation and will be the one to bear the cost of our response", Barak said during a visit to Ashkelon, adding that "an Israeli response is necessary and will be carried out."

The defense minister spoke in the wake of escalating rocket attacks that peaked Thursday with a direct hit on a home in Ashkelon, and Israel Defense Forces operations against militants which killed at least 18 Palestinians on the same day.

During his visit to the port town, Barak was debriefed by officers from the Southern Command, the Israel Police, rescue services officials and the mayor of Ashkelon on steps being taken in the city in light of the present security situation.

Barak also visited a house in the city hit by a Katyusha on Thursday.

Also Friday, the chairman of the Knesset Foreign Affairs and Defense Committee said the IDF must reoccupy part of the Gaza Strip for an unlimited time and overthrow the Hamas government.

"The State of Israel must make a strategic decision to order the IDF to prepare quickly to topple the Hamas terror regime and take over all the areas from which rockets are fired on Israel," MK Tzachi Hanegbi (Kadima) told Israel Radio. He said the IDF should prepare to remain in those areas for years.

MK Gideon Sa'ar (Likud) said his party would back an invasion of Gaza, though he fell short of advocating reoccupation.

"There is no doubt that the security response needs to include a ground component," said Sa'ar. He said the "takeover of territory in the northern Strip" from which the Palestinians launch rockets at Israel would reduce the barrages from Gaza.

Deputy Defense Minister Matan Vilnai went as far as threatening a "shoah," the Hebrew word for holocaust or disaster. The word is generally used to refer to the Nazi Holocaust, but a spokesman for Vilnai said the deputy defense minister used the word in the sense of "disaster," saying "he did not mean to make any allusion to the genocide."

"The more Qassam fire intensifies and the rockets reach a longer range, [the Palestinians] will bring upon themselves a bigger shoah because we will use all our might to defend ourselves," Vilnai told Army Radio on Friday.

Hamas official Sami Abu Zuhri said of Vilnai's comments: "We are facing new Nazis who want to kill and burn the Palestinian people."

Palestinians in Gaza fired about a dozen Grad rockets Thursday on the southern port city of Ashkelon, some 15 kilometers north of the Strip. A 17-year-old girl was lightly hurt in the rocket attacks and several others suffered from shock. The day before, a Sapir College student was killed in a rocket attack on Sderot. Fighting in Gaza also continued Thursday, with at least 18 Palestinians, including five boys and a 6-month-old baby, killed in Gaza air strikes.

Israeli military analysts say that as Ashkelon becomes a permanent target of Hamas missile attacks, an Israeli ground offensive is becoming inevitable and likely to occur sooner rather than later.

Such an offensive seemed to move one step closer Thursday, with Barak declaring that such an operation was "a real likelihood" - although he told Quartet representatives that it was not imminent, a position that appeared to be echoed by Prime Minister Ehud Olmert.

Barak also ordered rocket alert sirens activated in Ashkelon for the first time, starting Friday.

"The major ground operation is real and tangible," Barak told his security chiefs during a meeting Thursday, according to sources who took part in the meeting. "We are not afraid of it."

Meretz-Yahad chairman MK Yossi Beilin advocated a diplomatic solution rather than a military one.

"My solution is to reach a cease-fire with Hamas," said Beilin, who said Israel should also continue negotiation with the Palestinian Authority.

Beilin said Hamas has expressed an interest in a truce over the last few weeks and that it was irresponsible of Israel not to respond to them.

"There have been at least two requests from Hamas, via a third party, to accept a cease-fire," he said.

The government, for its part, has been sending mixed messages regarding the possibility of a ground offensive in Gaza.

Olmert appeared to suggest that a major Israeli ground operation against militants in the Gaza Strip was not imminent, saying Israel's fight against them was a "long process" and that there was "no magic formula" to halt frequent rocket attacks.

Public Security Minister Avi Dichter, who visited Sderot on Thursday, rejected proposals to reoccupy the Gaza Strip, calling them "populist ideas which I don't agree with, and in my opinion, no intelligent person does either."

Nonetheless, Israel's Foreign Ministry spokesman later said the violence "may leave us no choice" but to send troops back in, two and a half years after Israel ended its occupation of Gaza.

Early Thursday evening, a Katyusha-type rocket struck an apartment building in Ashkelon, crashing through the roof and slicing through three floors. No casualties were reported.

In another Grad-missile attack on Ashkelon, a 17-year-old girl was lightly hurt and several other people were treated for shock.

A senior Israeli security official said that the rockets fired into Ashkelon have been Iranian-made imports, with a range of about 22 kilometers, but some locally made rockets have fallen on the southern outskirts of the city.

The missiles, known as Grads, are taken apart, smuggled into Gaza through tunnels, and reassembled. But Hamas has only a limited supply, the source said.