Syrian rebels suffered a huge blow on Wednesday with 62 of them reported killed in an ambush, as Amnesty International said parts of second city Aleppo have been devastated.
In Washington, the CIA number two said the war poses the greatest threat to US security because of the risk of the regime falling and Syria becoming a weapons-rich haven for Al-Qaeda.
Government forces killed at least 62 insurgents in an ambush near Damascus, the Syrian Observatory for Human Rights said.
The regime's military said those killed were members of the jihadist Al-Nusra Front.
"At least 62 rebels fell as martyrs, most of them youths, and eight others are missing after an ambush by regime forces at dawn near the industrial city of Adra" northeast of Damascus, the monitoring group said.
A military source quoted by state news agency SANA said the "army carried out an ambush on a group of terrorists belonging to the Al-Nusra Front that was trying to infiltrate Eastern Ghouta and attack a military post."
"All the terrorists were killed and their arms captured," the source added, without giving a toll.
Adra, 35 kilometres (20 miles) from Damascus, is the gateway to Eastern Ghouta, a farming region on the eastern outskirts of the capital where the rebels have bases.
On July 21, 49 rebels were killed in fighting with loyalist forces, the Britain-based Observatory said.
The CIA's Michael Morell said in an interview in Tuesday's Wall Street Journal there are now more foreigners flowing into Syria each month to join Al Qaeda-affiliated groups than there were going to Iraq at the height of the war there.
Regime weapons "are going to be up for grabs and up for sale," as they were in Libya when Moamer Kadhafi fell, Morell said.
"It's probably the most important issue in the world today," he said, "because of where it is currently heading" -- towards President Bashar al-Assad's overthrow.
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The top US military officer, General Martin Dempsey, will visit Israel and Jordan next week for a trip focused in part on Iran and Syria.
Meanwhile, human rights group Amnesty International issued a report saying entire neighbourhoods of the northern city of Aleppo have been flattened over the past year.
"Aleppo has been utterly devastated, its people fleeing the conflagration in huge numbers," said Amnesty's senior crisis response adviser Donatella Rovera.
The report came as the London-based group released satellite images of several Aleppo districts, taken before and after clashes between government and rebel forces.
They show "alarming trends in how the conflict is being fought: with utter disregard for the rules of international humanitarian law, causing extensive destruction, death, and displacement," Amnesty said.
Aleppo, formerly Syria's commercial hub, became a battleground in July last year, when rebels launched an offensive.
Ever since, the city has fallen into a bloody stalemate, with much of eastern Aleppo in rebel hands and the west mostly under army control.
Civilians living in opposition-controlled areas suffer daily from both government bombing raids and abuse at the hands of some opposition groups, Amnesty said.
"Government forces have relentlessly and indiscriminately bombarded areas under the control of opposition forces across Syria, with civilians being at the receiving end of such attacks and at the same time also being subjected to abuses by some armed opposition groups," it said.
Many people displaced, especially to areas under rebel control, "receive little or no international aid, partly because they are in dangerous and difficult-to-access areas and also due to restrictions imposed by the Syrian government."
Amnesty reiterated its long-standing demand that the bloodshed in Syria, estimated to have cost more than 100,000 lives over the past 28 months, be referred to the International Criminal Court.
On the economic front, Syrian Oil Minister Sleiman Abbas said the government has paid more than $500 million (376 million euros) in subsidies to the oil sector over the past six months.
A statement obtained by AFP shows Syria is currently producing 39,000 barrels of oil a day, down sharply from 380,000 bpd before the start of the crisis in March 2011.
Because of the war, most oil must be imported, mainly from key regional ally Iran.