In an escalation of a trend that has left officials in Beirut on edge, Syrian forces crossed into Lebanon and shot dead a Syrian man in the eastern Bekaa Valley, security sources told Reuters on Friday.
The sources said the shooting occurred Thursday as Syrian soldiers pursued dissident Ali Al Khatib near the village of Arslan, where Syrian forces made a similar incursion two days prior.
The frontier between the two countries notoriously porous, where remote regions serve as havens for smugglers.
In recent weeks Syrian mechanized infantry and armor units have made numerous lightning raids across the border in pursuit of dissidents fleeing a brutal six-month crackdown by forces loyal to Syrian president Bashar al-Assad.
Syrian authorities blame armed groups backed by foreign powers for the violence, and say they have caught large quantities of weapons being smuggled into the country from Lebanon. In addition to the protest movement, they face a growing insurgency by army defectors led by dissident General Riad Bashar.
Lebanon's army did not comment on the incident.
However, Prime Minister Nijab Mikati has vowed to protect Syrian refugees in Beirut and said his government is watching border developments, especially in regions previously occupied by Syria, very carefully.
The United Nations says 2,900 people have been killed by Assad forces and that and at least 3,800 Syrians have taken refuge in Lebanon.