Israeli air raids on Syria at the weekend killed at least 42 soldiers, a watchdog said today, fuelling international concern over a spillover of the conflict, as Damascus warned it would strike back.
UN human rights investigator Carla del Ponte, meanwhile, said that rebels have used the deadly nerve agent sarin in their fight to oust Syria's regime, although inspectors later said there was no conclusive proof as yet.
"At least 42 soldiers were killed in the strikes, and another 100 who would usually be at the targeted sites remain unaccounted for," Syrian Observatory for Human Rights director Rami Abdel Rahman told AFP.
The strikes early on Sunday near Damascus were the Jewish state's second reported air raids on Syria in 48 hours. An early Friday raid had targeted a weapons storage facility at Damascus airport.
A senior Israeli source said the raids targeted Iranian weapons destined for the Lebanese militant group Hezbollah.
Iran and the Shiite group Hezbollah are steadfast allies of Syrian President Bashar al-Assad's regime, and arch-foes of Israel.
A Syrian official in Damascus, reached by phone from Beirut, warned "Syria will respond to the Israeli aggression and will choose the moment to do so."
"It might not be immediate because Israel now is on high alert," he added. "We will wait but we will answer."
UN leader Ban warned against any escalation of a conflict that has killed more than 70,000 people in Syria since it erupted in March 2011.
"The secretary-general calls on all sides to exercise maximum calm and restraint, and to act with a sense of responsibility to prevent an escalation of what is already a devastating and highly dangerous conflict," his spokesman Martin Nesirky said.
Ban spoke by telephone with Arab League chief Nabil al-Arabi, whose 22-member bloc demanded UN Security Council intervention to stop such Israeli attacks.
The EU also said it feared recent developments "risk dragging the region into an expanding conflict."
Russian President Vladimir Putin held telephone talks with Israeli Prime Minister Benjamin Netanyahu over the Syrian conflict, the Kremlin said Monday.
Putin and Netanyahu discussed the "situation in the region and the situation around Syria," Putin's spokesman Dmitry Peskov said in a statement to Russian news agencies, without giving further details.
The foreign ministry in Russia, the most powerful ally of Assad's regime, had earlier expressed concern over the air strikes.
And China implicitly criticised the strikes as Netanyahu arrived in Shanghai, saying "we are opposed to the use of force and believe that the sovereignty of any country should be respected".
The Syrian regime's main regional ally Iran denied the weapons targeted were from the Islamic republic.
A diplomatic source in Beirut told AFP the sites were the Jamraya military facility, a nearby weapons depot and an anti-aircraft unit in Sabura, west of the capital.
