Gaza City - Upping the rhetoric against the Hamas administration in the Gaza Strip, Israeli leaders hinted Tuesday that a strike against the Islamist movement in the salient could be launched in order to end rocket attacks on southern Israel.

"The state of Israel cannot live under these conditions in the long term," Prime Minister Ehud Olmert said while touring towns and villages along the Gaza border, which are frequent targets of missiles militants fire from the strip.

"The other side also knows that the Israeli government doesn't just know how to protect itself, but also knows how to strike," he said.

Deputy Defence Minister Matan Vilnai, who accompanied the premier, said that the recent escalation of rocket attacks "will end with a blow to Hamas' head."

But he said, in response to demands that Israel launch a wide- ranging ground offensive in the strip: "We should not be rushed. We know what needs to be done and we'll do it when the time is right, in order to produce the desired results."

Foreign Minister Tzipi Livni was more emphatic, telling a conference in Tel Aviv on Tuesday that in order to safeguard Israel's deterrence ability, "a (military) response is important; even if it does not halt the Palestinian rocket fire automatically."

"We are living in an area where image has meaning, and when the image is weakened, that harms Israel's deterrence capability," she explained.

"If Hamas knows that Israel won't be quiet when missiles fall on Ashkelon, they will feel the responsibility on their shoulders," she said.

A truce between Israel and the Gaza militias, which came into being on June 19, began to fall apart one month ago after Israel killed five militants in a raid to destroy a tunnel it said was being dug under the border to facilitate the kidnapping of soldiers.

Militants, who during the truce had sporadically fired rockets at southern Israel, renewed the barrages in earnest - according to the Israeli military, over 200 missiles and mortars have been launched since the Israeli raid on the night of November 4- 5 - and Israel retaliated by renewing its policy of targeting rocket-launching cells.

The renewed rockets on southern Israel have led Defence Minister Ehud Barak to order the Gaza crossings closed after each barrage, preventing the passage into the salient of humanitarian aid.

The crossings were opened Tuesday, after no rockets or mortars fell on Monday, and on Tuesday afternoon a ship carrying 11 pro-Palestinian activists docked in Gaza, the fourth vessel to break the Israeli siege.

The ship, which left Larnaca, Cyprus, on Sunday, carried on board several types of medicine for distribution in the strip. (dpa)