Hizbullah acknowledged that a truck full of ammunition intercepted by authorities in an east Beirut suburb on Thursday belonged to the group and demanded the government immediately release the shipment. The seizure and the harshness of Hizbullah's demand added to already high tensions in an ongoing power struggle between the US-backed government and the Hizbullah-led opposition seeking to topple it. Hizbullah's demand followed an announcement by Information Minister Ghazi Aridi that authorities had intercepted a truck full of ammunitions in a suburb east of Beirut on Thursday. The news came during a meeting of the Cabinet, which also discussed the overnight exchange of fire on the tense Israeli-Lebanese border. The shootout, which did not result in casualties, was the most serious clash since last summer's war between Hizbullah and Israel. "The preliminary information says the truck came from (eastern Lebanon's) Bekaa Valley," said Aridi, adding that an investigation was under way to determine the type of weapons and who they were intended for. Witnesses described it as a six-wheel truck, stopped in the Hazmiyeh suburb. Some unconfirmed reports said it contained mainly machine guns and other light weapons. A security official later said the ammunition included 20 Grad rockets and 20 rocket launchers concealed in bags of straw. Under a UN resolution that ended this summer's Israel-Hizbullah war, the group is banned from rearming. But the militants said in a statement Thursday that the government must abide by its own policy, proclaimed in 2005, to support the "resistance" in the south - which is Lebanese shorthand for the guerrilla. Israel has accused Hizbullah of rearming and has said its air force would continue to monitor Lebanon to prevent weapons shipments to the group. Only one similar incident took place during the summer war, when Hizbullah accused the army of seizing an ammunitions shipment. But Hizbullah is now talking from a position of strength, after its two ministers and four allies bolted out of the cabinet in November. The militants have since been leading protests and sit-ins to force Prime Minister Fuad Saniora to quit or give them and their allies more power. In a statement faxed to The Associated Press, Hizbullah said Lebanese customs officials had seized a "truck carrying ammunition for the resistance from the Bekaa to the south." It said the 2005 government's policy statement clearly affirmed the right of the group to continue its efforts to free remaining occupied Lebanese territories and confront Israeli threats. "Consequently, the concerned authorities must return the truck and the ammunitions to the resistance," Hizbullah said.