Lebanese and Israeli troops have exchanged fire in a fierce border battle that killed a senior Israeli officer, two Lebanese soldiers and a journalist after a row which started over the trimming of a tree.
It was the worst fighting since 2006 and underlined how easily tensions can re-ignite along the frontier where Israel and Hezbollah fought a war four years ago.
The violence apparently erupted after Israeli soldiers went to cut down a tree along the fence dividing the two countries.
The Shiite guerrilla force Hezbollah said it offered to help the Lebanese army but in the end did not get involved.
"We told our brothers, control yourselves and don't do anything," Hezbollah leader Sheik Hassan Nasrallah in a televised speech. But he warned his fighters would intervene if Israeli troops ever attack Lebanese forces again. "Any Israeli arm extended against the Lebanese military will be cut off by the resistance," he said.
The UN urged "maximum restraint" and said it was working with both sides to restore calm. After an initial clash of about five minutes, intermittent shelling and gunfire went on for several hours.
A Lebanese army officer said the battle started when Israeli troops tried to remove a tree from the Lebanese side of the border.
Ronith Daher, 32, a Lebanese journalist who was at the scene, said she saw a UN peacekeeper ask Israel not to allow the Israeli soldier to cross the fence and warned them the Lebanese troops would open fire. The Israelis proceeded, however, and Lebanese soldiers fired into the air. She said the Israelis fired back directly at the Lebanese soldiers.
The Israeli military's northern commander, Major General Gadi Eizenkot, however, accused Lebanese forces of shooting toward forces inside Israeli territory without any provocation." He said that while soldiers were removing bushes by the fence, Lebanese military snipers shot two officers who were more than 300 yards away from the fence.
A spokesman said Israel responded with infantry, tanks and artillery fire, and later sent helicopters and artillery fire at a Lebanese army base and command centre.