LEBANON BORDER, Aug 10, SPA-- As cease-fire negotiations appeared to stall, Israel lobbed artillery rounds into southern Lebanon early Thursday while troops backed by tanks and armored vehicles moved across the border. According to Lebanese military sources and U.N. observers, a vicious battle broke out between Israeli troops and Hezbollah fighters in Khiyam, which Israel says is a Hezbollah stronghold. In a written statement, the Israel Defense Forces said Hezbollah had been firing rockets from Khiyam into the Israeli cities of Metula, Kiryat Shmona and the Galilee panhandle. The Associated Press quoted a spokeswoman for the Jewish state as saying that the offensive was not part of an expanded campaign that Israel's Security Cabinet had approved on Wednesday. "It's a small operation that looks large from where we're looking right now, but this is not opening up any new front," spokeswoman Miri Eisen said. "It's taking care of one that has been consistently hitting Kiryat Shmona." West of the panhandle, dozens of Israeli soldiers were injured during fighting around Bint Jbeil, Lebanon, where Israeli troops have battled militants for much of the four-week conflict, the IDF reported. The IDF also reported that it sustained other casualties in the Lebanese towns of Aita Al-Shaab and Debel. At least 15 soldiers were killed in fighting, the most Israel has lost in a single day since the fighting began, the IDF said. As of 3 p.m. (8 a.m. ET) Wednesday, Hezbollah had fired 160 rockets into northern Israel, 22 of which landed inside cities, according to Israeli police. North of the border, Israeli airstrikes again hammered the Beirut suburb of Haret Hreik, once home to Hezbollah headquarters, according to the Lebanese Army. The Israeli Security Cabinet on Wednesday approved an expanded offensive in which Israeli troops could push up to the Litani River, 18 miles inside Lebanon. The decision is pending final approval from Prime Minister Ehud Olmert and Defense Minister Amir Peretz, according to the prime minister's office. About 10,000 Israeli troops are on the ground in southern Lebanon, according to Israeli military analysts.