A recent video shows Syrian rebels holding capture of a military airbase in Deraa on Thursday, as well as seizing a large stockpile of missiles and artillery.
The free Syrian army achieved a number of strategic victories on ground in the past week, including the capture of an oil field in the eastern province of Hasaka.
The rebels, from the Islamist Al-Nusra Front and the Muhajireen battalion, overran the base in Sfeira, east of Aleppo international airport, as well as seizing a large quantity of ammunition, the Syrian Observatory for Human Rights said.
The rebels geared up for a major battle against loyalists as the opposition said it refuses to accept President Bashar al-Assad in talks on the 23-month conflict.
The Britain-based watchdog also reported intermittent clashes around the Aleppo airport itself as well as around Nayrab airbase and another military complex, as the two sides squared up for a major fight.
Rebels seized the base on Wednesday after a battle that left at least 150 dead from both sides, among them senior army officers, according to the Observatory.
Regime tanks, meanwhile, shelled the town of Khan Sheikhun in the province of Idlib, killing at least 11 civilians, the Observatory said, adding that at least 107 people were killed in violence nationwide on Friday.
In Damascus, the army shelled the eastern district of Jobar where rebels have set up enclaves, the Britain-based group said.
It also said more than 100 civilians have been abducted in Idlib province in separate incidents, expressing alarm at what it called “sectarian kidnappings.”
As they have done every Friday, Syrians protested across the country after weekly prayers to denounce what they called the “inaction” of the international community over the Syria crisis.
“In spite of you, O Bashar, we have our freedom!” chanted protesters in Sukkari, a rebel-held district of Aleppo.
State television broadcast footage of what it said was a pro-regime demonstration in Aleppo, and said residents had called for “armed men to leave their city.”
The International Committee of the Red Cross in Geneva said the plight of civilians in Syria has reached catastrophic levels.
“After two years with no end to the military conflict, the situation of the civilian population has reached nothing short of catastrophic” proportions, ICRC Director of Operations Pierre Kraehenbuehl told reporters.
The ICRC has been aiding some 1.5 million Syrians, via the Syrian Arab Crescent, in a conflict that the UN says has left some 70,000 people dead.
The United Nations has also said the number of Syrians who have fled the country could hit 1.1 million by June.
Customs officers in Finland, meanwhile, said they had seized spare parts for tanks in a container en route from Russia to Syria on board a Finnish ship docked at Helsinki’s Vuosaari port in January.
The European Union has banned all sales, delivery, transfers and exports of weapons to Syria.