Fighting on the Lebanese-Israeli border is at its most intense in months, reports Mohalhel Fakih from Beirut Hizbullah fighters killed an Israeli soldier and wounded five others in tit-for-tat attacks across the volatile Shebaa Farms border. The clashes were the most serious to have taken place since January. Still, cross-border fighting remained within the rules of engagement that both sides set after Israel withdrew troops from southern Lebanon following a 22-year occupation. "I don't think there will be an escalation. Both sides are still playing by the rules of the game. They are being careful to avoid an escalation, which can only be maintained if there are no civilian casualties on both sides. The clashes have been confined to military targets," Timur Goksel, who from 1979 to 2003 served as a spokesman for the United Nations Interim Force in Lebanon (UNIFIL), told Al-Ahram Weekly. Hizbullah on Friday launched at least 50 mortar rounds at Israeli positions in the Shebaa Farms area. These were followed by Israeli airstrikes on the outskirts of Lebanese villages, causing material damage and killing livestock. Hizbullah and Israel provided conflicting accounts of how the fighting erupted. Hizbullah said Israeli forces crossed the Blue Line -- demarcated by the UN in 2000 -- and that it was only when they approached Shia positions that fighting erupted. According to Hizbullah, it was Israel's incursion that led "to the deaths and injuries in enemy ranks". However on Sunday, Israel's Deputy Defense Minister Ze'ev Boim accused Hizbollah fighters of crossing the border and planting explosives around a military outpost, strongly denying Israeli soldiers had violated the Blue Line. He also sent chilling warnings to Beirut and Damascus against any tensions. Israel's military, on the other hand, said one soldier -- whose death is the first to have been declared as consequent of fighting in this region since January -- was killed in cross- border clashes. "There was sort of a bait that was planted. Hizbullah placed roadside bombs on the border but there are no border marks. The Blue Line is an imaginary line. There is a fence, but it does not represent the border; anyway it is difficult to plant bombs right along the fence. Since there is no fixed line you can easily say they crossed into Lebanon, and that there is a right to strike," Goksel, who is now a university lecturer in Beirut, said. Tensions were high all week. Israeli fighter jets carried out mock raids across Lebanon on Wednesday, drawing anti-aircraft fire from Hizbullah. The usual Israeli strategy was successful as it could use the pretext that shrapnel was falling near border settler communities. Israeli warplanes then struck at two empty Hizbullah positions deep in the heart of the former occupation zone. Hours later Israeli troops said they had foiled the attempts of two groups of infiltrators in the Shebaa Farms to cross the border. Israel was defiant in defence of its incursions. "An escalation will not be convenient for Israel but it will be catastrophic for Syria and Lebanon," the head of Israel's northern command Major General Benny Gantz said after Friday's violence. Hizbullah constituted the main driving force of the resistance that led to the withdrawal of Israel in 2000. Lebanon, for its part, filed a complaint with the UN. Foreign Minister Jean Obeid said Beirut had asked the Security Council to help end Israeli violations of Lebanese airspace, calling also for an investigation into the violence. An- Nahar, the Lebanese daily, said a joint Lebanese-UN investigation found Israeli troops had indeed charged into Lebanese territory. UN Secretary-General Kofi Annan's Personal Representative to South Lebanon Staffan di Mistura urged restraint and strongly criticised continued Israeli overflights over Lebanon. "The overflights have to end. They have been bothering the UN for a long time. I know that in the past the US Embassy also got involved to help stop the flights, but they continue," Goksel told the Weekly, adding that both sides were forced into military confrontation to "play to their [respective] public opinions". But he added that Israel and Hizbullah have shown willingness to prevent an escalation by avoiding civilian targets. He also said he does not expect the latest bout of violence to affect ongoing German-mediated prisoners exchange talks. "I don't expect the fighting will affect swap talks, which I understand are moving in a positive direction. I think we will see developments soon," Goksel said. Media reports in Lebanon and Israel both indicate that a new round of negotiations is edging close to a breakthrough. The reports refer to information on missing Israeli airman Ron Arad and the release of Lebanese and Palestinian detainees held in Israel. In January, Hizbullah freed an Israeli reserve colonel and returned the bodies of three soldiers in exchange for more than 400 Arab prisoners. Syria, the Lebanese government and Hizbullah in May 2000 declared the Shebaa Farms area Lebanese land occupied by Israel. The UN says it is Syrian land, occupied when Israel annexed the Golan Heights.