Israeli Foreign Minister Tzipi Livni called Thursday for an immediate military response to Qassam fire by Palestinian militants in the Gaza Strip.
Her remarks came hours after a rocket hit the Negev area earlier in the day, the fifth after the Egyptian-brokered truce went into effect last Thursday.
"There was a similar breach of the truce several days ago," Livni was quoted by the website of local daily Ha'aretz as saying at the start of her meeting with Norwegian Foreign Minister Jonas Gahr Stoere. "I don't care who fired. Every breach must be met with an immediate military response. I made my opinion clear to both the prime minister and the defense minister following the first infraction, and I will make clear to my foreign counterparts too."
Meanwhile, Israeli Defense Minister Ehud Barak said that "only deterrent military strength and superior excellence lead to a swift victory, and they are what will lead to peace. And when achieved, it will be stable and long-lasting."
Earlier, a rocket hit an open area of the industrial zone outside the city. There were no reports of injuries or damage, according to army sources.
The Fatah-affiliated Aksa Martyrs Brigades claimed responsibility for the attack. In a text message sent to reporters, it said "the truce must include the West Bank and all sorts of aggression must stop."
It was the third time that the fragile cease-fire agreement was violated by attacks.
On Tuesday, the Islamic Jihad fired three Qassam rockets at the Sderot area, and a mortar shell was fired at Israel the previous day.
On Thursday morning, Hamas accused Israel of violating the terms of the Gaza cease-fire a day after Israeli Defense Ministry decided that Israel would keep the Gaza border crossings closed Thursday, except for special humanitarian cases, in response to Tuesday's Qassam rocket attacks.
"If the crossings remain closed, the truce will collapse," Hamas spokesman Sami Abu Zuhri said Thursday morning.
The spokeswoman of Israel Defense Forces (IDF) told Xinhua that the Sufa crossing, the Nahal Oz fuel terminal and the Karni crossing and the Kerem Shalom crossing were closed since early Wednesday morning for the transfer of food, medicine and humanitarian equipment. The Erez crossing in the northern Strip will open for the passage of Palestinians into Israel for humanitarian treatment.
It was unclear when the transfer of goods into Gaza would be resumed.
Local daily Jerusalem Post reported Thursday that Israeli Defense officials planned to open the Gaza crossings on Friday if there were no more violations of the cease-fire.