Lebanon's army said it fired tear gas at Israeli forces over the border Saturday in response to smoke bombs fired at its troops, though Israel said Lebanon started the confrontation.
Tensions have flared along the frontier this summer, with rockets fired at Israel during flare-ups of Israeli-Palestinian violence, and members of the heavily armed Lebanese group Hezbollah or its supporters facing off with Israeli forces.
"Elements of the Israeli enemy violated the withdrawal line and fired smoke bombs at a Lebanese army patrol that was accompanying a bulldozer removing an earthen berm erected by the Israeli enemy north of the withdrawal line, the blue line, in the Bastra area," the Lebanese army said in a statement.
The current demarcation line between the two countries is known as the Blue Line, a frontier mapped by the United Nations that marks the line to which Israeli forces withdrew when they left south Lebanon in 2000.
"The Lebanese patrol responded to the attack by firing tear bombs ... forcing them to withdraw to the occupied Palestinian territories," Lebanon's army added.
The Israeli military said it was Lebanon that started the violence.
"A short while ago, IDF soldiers spotted an engineering vehicle's shovel crossing the Blue Line from Lebanon into Israeli territory in the area of Mount Dov," a statement from the military said. "In response, IDF soldiers used riot dispersal means."
"The vehicle returned to Lebanese territory," the military said.
UNIFIL, the U.N. peacekeeping force in the area, said there had been tension on Saturday.
"UNIFIL is in touch with the parties to decrease tensions and prevent a misunderstanding. At the moment we are on the ground, monitoring the situation and trying to bring calm back to the area," spokesperson Andrea Tenenti said.