Syria has accused Israel of giving military support to rebels after air strikes on the edge of the capital, Damascus.
The government says Israel hit a research centre and other military sites causing deaths and injuries and widespread damage.
The Israeli strikes showed co-ordination with "terrorists" including al-Qaeda linked militants, the foreign ministry said. Syria's government refers to rebels fighting against it as terrorists.
Israeli sources said weapons bound for Hezbollah in Lebanon were the target.
Israel has repeatedly said it would act if it felt advanced weapons were being transferred to militant groups in the region, especially Hezbollah.
On Friday, Israeli aircraft hit a shipment of missiles near the Lebanon border, according to unnamed US and Israeli officials.
In the latest attack, Damascus was shaken by repeated explosions coming from the north-western suburbs.
Amateur video footage and eyewitness testimony suggested rocket attacks had hit weapons dumps, triggering dramatic orange-flamed blasts.
The area houses numerous military facilities, including the Jamraya research centre, designated by Syria as a scientific research centre "in charge of raising our level of resistance and self-defence".