A landmine explosion on Saturday night near the Lebanese border left three Syrian men badly wounded, a medical official in the northern Lebanese province of Akkar told AFP.
Two of the men had to have their legs amputated, the official added, speaking on condition of anonymity.
Syria's state news agency SANA said regime forces "on Saturday night foiled an attempt by armed terrorist groups to illegally cross the border from Lebanon" into the central Syrian province of Homs.
Lebanon's northern and eastern borders have seen frequent exchanges of fire in recent weeks, some of them deadly, as well as shelling from Syria into Lebanon.
Syrian troops have laid landmines on the border with north Lebanon, sparking outrage from human rights organizations.
Last week, Beirut and Damascus traded accusations of violating each other's territory.
President Bashar al-Assad says Lebanon does not do enough to stop "armed terrorists" and weapons from being smuggled across the border into Syria.
Lebanese President Michel Sleiman last week accused Syria of violating Lebanese territory after a house in the eastern Qaa region was hit by a blast and shells fired from Syria hit several villages along the northern border.
The protest was the first of its kind by a Lebanese president since Syrian troops withdrew from Lebanon in 2005 after nearly three decades of political and military hegemony over its smaller neighbor.