Russia has expressed concern at an alleged Israeli attack on Syria, saying such a strike would be an unacceptable violation of the UN Charter.
Syria’s army said Israeli jets had targeted a military research centre north-west of Damascus on Wednesday.
It denied reports that lorries carrying weapons bound for Lebanon were hit.
Russia has steadfastly refused to denounce Syrian President Bashar al-Assad during the 22-month conflict that has killed more than 60,000 people.
The Syrian army statement, carried on state media, said Israeli fighter jets had carried out a direct strike on a scientific research centre in Jamraya, killing two people and injuring five.
The Russian Foreign Ministry said: “If this information is confirmed, then we are dealing with unprovoked attacks on targets on the territory of a sovereign country, which blatantly violates the UN Charter and is unacceptable, no matter the motives to justify it.”
Relations between Russia and Israel have been improving in recent years as trade and economic ties have grown stronger, says the BBC’s Steve Rosenberg in Moscow.
But Moscow is a close ally of President Assad, which would explains its concern at the reports, our correspondent adds.
Missiles heading for border?
The attack came as Israel voiced fears that Syrian missiles and chemical weapons could fall into the hands of militants such as Lebanon’s Hezbollah.
Israel and the US have declined to comment on the reported incident.
Lebanese security sources, Western diplomats and Syrian rebels say the target was an arms convoy near Lebanon’s border.
The Lebanese military and internal security forces have not confirmed the reports, but say there has been increased activity by Israeli warplanes over Lebanon in the past week, and particularly in recent hours.
For its part, Lebanese Shia militant group Hezbollah said the target was the Jamraya centre, condemning it as “an attempt to thwart Arab military capabilities” and pledging to stand by its ally Mr Assad.
BBC Middle East correspondent Wyre Davies says that while none of the reports can be verified, some well-placed diplomats and military sources say they would not be surprised if Israel had acted, given the recent instability in Syria.
The Syrian army statement said the Jamraya centre – which was focused on “raising our level of resistance and self-defence” – was damaged in the attack along with an adjacent building and a car park.
It said “armed terrorist gangs”, a term the government uses to describe rebel groups, had tried and failed repeatedly to capture the same facility in recent months.
The statement specifically denied reports that an arms convoy had been hit.
The Jerusalem Post said the description of the facility fitted that of Syria’s Scientific Studies and Research Centre, believed to be the state organisation responsible for developing biological and chemical weapons.
Hours earlier, unnamed Lebanese security sources reported that Israeli warplanes had struck lorries carrying missiles towards the Lebanese border.
The Associated Press quoted a US official as saying the lorries were carrying Russian-made SA-17 anti-aircraft missiles.
Correspondents say Israel fears Hezbollah could obtain anti-tank and anti-aircraft missiles, thus strengthening its ability to respond to Israeli air strikes.
However, an attack on the Syrian side could cause a major diplomatic incident, they say, as Iran has said it will treat any Israeli attack on Syria as an attack on itself.
The reported attack came days after Israel moved its Iron Dome defence system to the north of the country.
Israel has also joined the US in expressing concern that Syria’s presumed chemical weapons stockpile could be taken over by militant groups, although there is no evidence that the convoy was carrying such weapons.
Israel believes Syria received a battery of SA-17s from Russia, analysts say, after an alleged Israeli air strike in 2007 that destroyed a Syrian nuclear reactor near Deir ez-Zor in eastern Syria.
The US government said in 2008 that the reactor was “not intended for peaceful purposes”.