With a fresh influx of weapons, opposition fighters have made significant gains in the past weeks, particularly in the southern province of Daraa, where rebels have been advancing in the region between the Jordanian border and the capital, Damascus.
The province of Homs and its capital of the same name were the scenes of some of the heaviest fighting during the first year of Syrian conflict. The violence has escalated there in recent weeks, with Syrian war planes hitting the city daily.
In the past two days, troops have clashed with rebels on the edges of the province along the Lebanese border in some of the worst fighting in the area in months.
On Friday, sporadic explosions inside Syria could be heard from the Lebanese side of the border and an Associated Press reporter said Syrian warplanes carried out at least one airstrike inside Syrian territory.
The border area is strategically important to both sides fighting in Syria's civil war and battles there have been frequent in past weeks, particularly in and around the town of Qusair in Homs province. The area is considered vital to the Syrian regime because of its location along a road linking Damascus with the city of Homs, a strategic supply route for the military.
The Britain-based Syrian Observatory for Human Rights said Friday's clashes between soldiers and opposition fighters were concentrated around Qusair. There were no immediate reports of casualties.
Overlooking Qusair from the Lebanese side are villages populated mostly by Shiite Muslim supporters of the Hezbollah militant group, who have supported Assad's regime during Syria's two-year conflict. The rebels fighting to topple Assad, a member of the minority Alawite sect, are overwhelmingly Sunni Muslim. The Alawites are an offshoot of Shiite Islam.
In the Lebanese village of al-Qasr, which is on the opposite side of the border from Qusair, residents said they had gotten used to the shelling.
"Yesterday, the explosions were nonstop," Ali Nasereddine said, sitting in the garden of his two-story house, fewer than 100 meters (yards) from a Syrian army post.
A funeral was held for Riyad Kinyar, a Shiite Syrian soldier who was wounded in the fighting Thursday and died upon arrival in a hospital in al-Qasr. Later Friday, the soldier was taken across the border to his hometown of Matraba for burial. Shooting in the air—a sign of mourning—could be heard across the border.
The Syrian conflict started with largely peaceful protests against Assad's regime in March 2011 but eventually turned into a civil war that has increasingly taken sectarian overtones. More than 70,000 people have been killed in the war, according to the United Nations.
Also on Friday, Syrian warplanes carried out airstrikes around the country, hitting targets in Daraa in the south, in Hasaka province in the north east near the border with Turkey and in the northern city of Aleppo, parts of which have been under rebel control since last summer.
The airstrikes come a day after a U.S.-based human right group accused the Syrian air force of carrying out indiscriminate attacks on civilian areas around the country—attacks the group claims amount to war crimes. More than 4,300 people have been killed in aerial bombardments since last summer, Human Rights Watch said in a report Thursday.
In Tehran, Iranian state broadcaster Irib said an Iranian journalist was wounded on Thursday in a shooting near Damascus.
The Irib report on Friday blamed "terrorists" for the attack—a term the Syrian regime uses for rebels. Iran has backed Assad's regime in the civil war.
Irib says the unidentified journalist was shot in the abdomen and was treated in a hospital in the capital.
An Iranian official in Damascus told The Associated Press that the journalist was driving his car on a highway linking the city with the Damascus airport when he was shot. The official identified the journalist as Mohsen Khazaei of Iran's TV News Network Shabake Khabar.
He was treated in a hospital and released on Thursday, the official said. He spoke on condition of anonymity because he was not authorized to release the information on the incident.
AP writer Albert Aji in Damascus, Syria, contributed.