Warplanes belonging to the Bashar Assad regime launched up to 50 air strikes since the beginning of Saturday on Zabadani town, the Syrian Observatory for Human Rights (SOHR) reported.
The city of Zabadani, over which Assad forces have long sought to gain control, is located near the Beirut-Damascus highway which connects both countries.
Capturing it would be a major boost for Assad’s withering government.
Zabadani, once a popular resort city, was part of a major supply route for weapons that were sent from Syria to Hezbollah militants before the outbreak of the Syrian conflict in 2011 .
In recent months, the Lebanese Shiite Hezbollah have increased their assaults on opposition outposts along the Qalamoun mountains region sprawling along the Lebanese-Syrian border in an effort to force opposition fighters to take a deal that would make them leave Zabadani without their weapons, Asharq al Awsat has learned.
“Hezbollah is pushing in the direction of a settlement that would allow fighters to leave the city of Zabadani without their weapons,” a Syrian opposition official told Asharq Al-Awsat.
“The militia has stepped up attacks on the opposition-held city since Wednesday after capturing Zabadani valley and blowing up a tunnel used by the opposition fighters for supplies,” the official said.
The statement was released after Ahrar al Sham, one of the opposition factions controlling parts of Zabadani, were negotiating with international sides to secure “a safe exit” for its fighters after enduring weeks of heavy bombardment.
The following claims were denied by the source adding that Hezbollah is “pushing for a similar settlement.”
“But we cannot count on Hezbollah as it will break its promises,” the opposition official stated.
Aides to UN Envoy to Syria Staffan de Mistura will negotiate the current situation in Zabadani with 11 opposition factions, including Ahrar Al-Sham, in Istanbul, Turkey, on Saturday, German press agency Deutsche Presse-Agentur (DPA) has reported.
An unnamed Syrian opposition official said that Staffan de Mistura will be represented by his deputy Ramzy Ezzeldin Ramzy, current head of the mission of the League of Arab States to Austria and permanent observer to the United Nations and other international organizations in Vienna, the DPA stated.
Representatives of the opposition fighting factions participating in the meeting will brief Staffan de Mistura’s deputy about the massacres committed by the Syrian army in Zabadani and urge him to include the information in the document that the envoy is expected to submit to the UN by the end of July.
Since 2011, a civil war has pitted regime troops against opposition forces in Syria.
So far, the Syrian civil war has resulted in the death of more than 220,000 people and displaced almost half of the country's population according to UN estimates.
Turkey, which hosts the largest number of refugees in the world, provides refuge for an estimated 1.8 million Syrian refugees - including around 200,000 from Kobane - more than any of Syria’s other neighbors.
More than 6.7 million people have fled Syria, while millions of others have been displaced internally.