Both activists said the rebels shot down a fighter jet near the oil field Sunday. It was not clear if the warplane was taking part in fighting in the area.
Abu Leila said that the oilfield had been functioning up until shortly before the rebels seized it. It was not clear whether the facility was damaged in the fighting or sabotaged by regime forces.
Analysts say the rebels would not benefit economically from capturing the oil filed, although the opposition's latest conquest could reduce crude supplies available to the government.
"It's another blow to Assad in terms of ... the oil available to him," said Robin Mills, head of consulting at Manaar Energy Consulting & Project Management in Dubai. The capturing of Al Ward is largely symbolic, Mills added. The rebels face serious challenges getting much — if any — of the captured oil to the market since the main export pipeline along the Mediterranean coast remains under government control.
"I don't see how they can export the oil that way," Mills said. "And even if they could, I don't see that anyone would pick up that oil."
In the past year, Syrian officials have repeatedly accused rebel units of targeting the country's infrastructure, including blowing up oil and gas pipelines in the energy-rich northeast of the country.
Syria exported some 150,000 barrels of oil a day before European and US imposed sanctions took effect. In 2010, it earned $4.4 billion by selling to EU countries alone.