IAF aircraft on Saturday night carried out two air-strikes against Palestinian rocket-launching squads in the Gaza Strip. Palestinian sources reported that two terrorists were injured in the second attack, one of them critically. Some 20 Kassam rockets and mortar shells pounded the western Negev over the weekend as Palestinian terror factions in the Gaza Strip intensified their attacks on Israel. A rocket was also fired on Saturday night into Ashkelon, causing no injuries or damage. Another rocket struck Sderot, and the others hit open areas near the city and within the Gaza Strip. No casualties or damage were reported. Defense Minister Ehud Barak decided Saturday night to keep the border crossings between Gaza and Israel closed on Sunday in the wake of the ongoing rocket and mortar shell fire. On Sunday morning, a rocket landed in the Eshkol region. No casualties or damage were reported. Palestinian groups said the weekend rocket barrage was in response to violence by settler against Arabs in Hebron, which broke out Thursday night following the evacuation of the city's disputed Beit Hashalom. Defense officials said that despite the escalation in rocket attacks, Defense Minister Ehud Barak was not in favor of a large IDF operation in the Gaza Strip. In recent weeks, one of Barak's top aides, Amos Gilad, has held a number of high-level talks with the Egyptians about extending the cease-fire between Israel and Hamas, which is due to expire on December 19. "Now is not the time for a large-scale operation, although this could change the moment many people are killed in a Kassam attack," one official said Saturday. Palestinians claimed that an IDF tank shell had killed a Popular Resistance Committees operative in central Gaza. The IDF denied the report and said that its tanks did not fire into Gaza on Saturday. Also Saturday, Egyptian police found a massive arms cache in Sinai, according to the Falastin al-Youm news Web site. According to the report, Egyptian troops found two weapons caches in the north and center of the peninsula, one of which, buried deep underground, contained more than 250 kilograms of dynamite. In the other cache, 211 anti-aircraft missile shells were discovered. The weapons were in all likelihood intended for the Gaza Strip, and the smugglers who hid them in the desert were still at large. The World Bank and the International Monetary Fund warned Saturday that Gaza's severe cash shortage might cause local banks to collapse. The warnings came in response to Israel's continued refusal to allow Palestinian banks to transfer cash to their Gaza branches. The cash shortage means thousands of Palestinian civil servants may not be able to withdraw their salaries before the Id el-Adha holiday this week. Monetary officials estimate Gaza banks hold less than a quarter of the cash needed to pay government wages. Jerusalem Post staff and AP contributed to this report.