Residents in villages scattered along the northern Lebanese border said they heard heavy shelling overnight in a Syrian city about 3 miles over the border, The Daily Star newspaper in Lebanon reports.
Security sources told the newspaper that Syrian warplanes were seen hovering over Lebanese districts near the border Thursday morning local time.
Damascus has said anti-government forces have taken position inside Lebanese territory and were using area villages to ferry weapons across the border.
The escalation of conflict in Syria has sparked concerns that the crisis could engulf Lebanon. Damascus had considerable influence over affairs in Beirut before a revolution in Lebanon in 2005 forced Syrian forces out of the country.
The U.N. Security Council has been deadlocked over the Syrian crisis. U.N. Secretary-General Ban Ki-moon told member states to not stand by "while the increasing sectarian violence spirals out of control, the humanitarian emergency escalates and the crisis spills over borders."
The Lebanese military announced plans to ramp up security measures. Pope Benedict XVI is to make a three-day visit to the country next week.