The Syrian regime has resorted increasingly to air strikes and artillery to stem the advancement of fighters on the ground.
Air and artillery bombardments have focused on Daraya and the nearby town of Mudamiyeh in recent weeks, raising fears of a major ground assault
Clashes also erupted in the Palestinian camp of Yarmuk in the south of the capital on Saturday between armed opposition and troops backed by pro-regime Palestinian fighters, the Observatory reported.
The outskirts of Damascus have been at the heart of fighting this month as the regime launches operations to reclaim territory within eight kilometers of the city.
With opposition fighters edging into the capital, a senior NATO official said that Assad is likely to fall and the Western military alliance should make plans to protect against the threat of his chemical arsenal falling into the wrong hands.
NATO's U.S. commander accused Syrian forces on Friday of firing Scud missiles that landed near the Turkish border; however, the Syrian government denied the claim.
Batteries of U.S.-made Patriot missiles, designed to shoot down the likes of the Scuds are about to be deployed by the U.S., German and Dutch armies, each of which is sending up to 400 troops to operate and protect the rocket systems.
Foreign Minister Walid al-Moualem told U.N. humanitarian chief Valerie Amos that U.S. and EU sanctions on Syria were to blame for hardships in his country and urged the United Nations to call for them to be lifted.
The World Food Programme says as many as a million Syrians may go hungry this winter, as worsening security conditions make it harder to reach conflict zones.
The 21-month old conflict, which resulted to more than the death of 40,000 syrians, has led to food shortages across the country, and residents of the northern city of Aleppo say fist fights and dashes across the civil war front lines have become part of the daily struggle to secure a loaf of bread.