Syria has accussed rebels opposed to President Bashar al-Assad of attacking Aleppo with a chemical weapon, killing 15 people.
The state-run SANA news agency said Tuesday the rebels fired a rocket with "chemical materials" on the Khan al-Asal area of the northern province.
Earlier Tuesday, the opposition Syrian National Coalition chose U.S.-educated former businessman Ghassan Hitto as provisional prime minister to administer the areas rebels have seized from Syrian forces.
Hitto received 35 of the 48 votes cast by members of the opposition coalition meeting in Turkey. He has lived in the United States for decades, but recently moved from Texas to Turkey to help coordinate aid to rebel-held areas.
More than 100 countries have recognized the opposition coalition as the legitimate representative of the Syrian people, including the United States, Britain, France and Turkey.
Gas cylinders are displayed for sale on a street in Aleppo, March 24, 2013.
A man sells clothes in Aleppo March 24, 2013.
Free Syrian Army fighters carry weapons while walking down a debris-filled street in Aleppo March 19, 2013.
This citizen journalism image provided by the Aleppo Media Center shows Syrians searching for dead bodies in the rubble of buildings hit by Syrian airstrikes, Aleppo, March 20, 2013.
Syrian President Bashar al-Assad and his wife Asma visit families of students killed during clashes between forces loyal to him and their opponents in Damascus in this handout photograph released by Syria's national news agency SANA on March 20, 2013.
Residents and medics transport a Syrian Army soldier, wounded in what they said was a chemical weapon attack near Aleppo, to a hospital, March 19, 2013.
People wounded in what the Syrian government said was a chemical weapons attack breathe through oxygen masks as they are treated at a hospital in Aleppo, March 19, 2013.
Girls paint their faces with colors of the Syrian revolutionary flag during a fesitval, in Aleppo, Syria, March 20, 2013.
A citizen journalism image of black smoke rising from a building hit by Syrian government shelling, Aleppo, March 19, 2013.
On Monday, Syrian warplanes fired missiles into northern Lebanon, a move the United States calls a "significant escalation" in the conflict between the Syrian government and rebels opposed to President Assad.
There is no word on damage or casualties from the shelling. This is the first time Syrian forces have fired at suspected rebel targets inside Lebanon, which is struggling to stay neutral in the Syrian civil war.
Earlier Monday, U.S. Secretary of State John Kerry said the United States does not oppose British and French efforts to arm the Syrian rebels.
Last week, France said it would work with Britain to send weapons to the rebels if the European Union does not ease its arms embargo.
EU foreign ministers plan to meet this week in Dublin to address the issue. Several EU members have expressed concerns that a flood of weapons into Syria would only add to the bloodshed.
The Britain-based Syrian Observatory for Human Rights said 110 people died in fighting across Syria on Monday.