Lebanon on Monday condemned the spillover of fire from Syrian rebel and regime forces onto its territory and said it would protest to the Arab League after artillery fire killed two people on Sunday.
"The safety of every Lebanese citizen and village is the responsibility of the Lebanese state, and any attack from any side is unacceptable," Social Affairs Minister Wael Abu Faour said after a ministerial meeting.
He said the foreign ministry would "undertake all necessary measures and communications to ensure all sides bear their responsibilities and do not repeat such attacks."
Abu Faour said the measures would include "the preparation of a memorandum to the Arab League," which would "protest... any attack regardless of which party was responsible for it."
The decision, taken by select ministers of the Hezbollah-dominated caretaker government, comes a day after two separate incidents of fire spilling over from Syria.
Shellfire from Syrian has regularly hit Lebanon, on occasion killing Lebanese, but Sunday's incidents were the first deaths in Hezbollah strongholds in the border region, reportedly from rebel fire.
Security sources reported further shelling on Monday, with two shells landing in the town of Qasr, where one person was killed a day earlier.
Beirut, which has officially followed a policy of "dissociation" from the Syrian conflict, has been reluctant to publicly blame either regime forces or rebel fighters for fire hitting its territory.
The war in neighbouring Syria has exacerbated existing tensions in Lebanon's multi-confessional population and fractious political system.
Abu Faour said the military was taking unspecified measures "to protect Lebanese citizens from any attack," without detailing whether the army would return fire across the border.
After the attacks on Sunday, the Lebanese army said its units "were deployed widely across the area and took measures in the field necessary to protect people and respond to the source of the attack as appropriate."
A security source told AFP on condition of anonymity that two shells hit Qasr on Monday, although no casualties were reported.
Syrian rebel commanders reached by AFP via the Internet confirmed insurgents had fired shells into Lebanon on Saturday and Sunday, but denied there were any attacks on Monday.
"Yesterday (Sunday), Hezbollah bombarded Qusayr, Nahriyeh, Burhaniyeh and Saqarji (near the Lebanese border) from its positions in Qasr and Hosh Sayid Ali. They bombed civilians and killed many women and children," said Abu Oday, a commander of the rebel Independent Farouq Division.
"If we have to, we will target civilians just like they do. Our civilians are not less valuable than theirs. Hezbollah is killing arbitrarily in Syria," he said.
"Yesterday, we responded. We hit back at Hezbollah's positions," he added.
Another rebel leader, Abu Ahmad, said insurgents did not fire into Lebanon on Monday.
"We are giving the Lebanese authorities an opportunity to respond, to take practical steps to put a stop to their shelling, before we respond again."
Meanwhile, residents of Lebanon's eastern Bekaa valley, a Hezbollah stronghold, told AFP that the bodies of five Hezbollah fighters killed in Syria were brought back on Sunday and Monday for burial.
"Yesterday, we buried a Hezbollah martyr, Assaad Ali Assaad, who was killed in Syria some days ago", said a resident of Khraybeh in eastern Lebanon.
A security source in Hezbollah stronghold southern Lebanon meanwhile told AFP on condition of anonymity that four other fighters from the region had also been killed in Syria.