Lebanese President Michel Sleiman has criticised Syria for a cross-border raid that he said targeted an ambulance in the east of the country, causing no injuries.
Local officials said the attack was carried out on Monday night by Syrian warplanes that fired at an area in the Arsal region of Lebanon, which has regularly been targeted by cross-border strikes.
In a statement on Tuesday, Sleiman said "an ambulance was targeted by Syrian rockets" and called for humanitarian bodies to be protected from "conflict and hostilities."
Local officials confirmed the attack.
"Syrian war planes targeted an ambulance in the Wadi Hmeid area of Arsal, but there were no injuries," an official told the AFP news agency on condition of anonymity.
A security source said planes had fired five rockets in the attack.
The Arsal area is broadly supportive of the uprising against Syrian President Bashar al-Assad. The mountainous area has long been a smuggling haven, with multiple routes into Syria that have been used since the conflict began in March 2011 to transport weapons and fighters.
Fighting in northern Syria
Meanwhile, Syrian activists said on Tuesday that government airstrikes targeted rebel positions near the strategic northern city of Maaret al-Numan.
The UK-based Syrian Observatory for Human Rights says the airstrikes were followed by heavy clashes, and said there were casualties in the fighting, but gave no specifics.
Rebels captured Maaret al-Numan a year ago. The city is strategic because it sits astride a major supply route linking the capital, Damascus, with Syria's largest city and commercial hub, Aleppo, in the north.
Fighting has flared up there in recent days, even as government forces and opposition fighters remain locked in a bloody, block-by-block fight for Aleppo since rebels launched an assault on the city 15 months ago.