Russia urged its Middle East ally Syria on Tuesday to refrain from using chemical weapons despite its threat to unleash the previously unreported arsenal in case of a foreign attack.

The foreign ministry said it "would like to underline that Syria joined" a Geneva protocol on the non-use of such weapons and "presumes that the Syrian authorities will continue to rigorously abide by its assumed international obligations".

Syria's threat Monday drew immediate and sharp condemnation from both the United States and Syrian neighbour and foe Israel.

But Russia took more than a day to formulate a response before issuing a carefully worded statement that demanded compliance with international treaties while not directly blaming Syria for making the threat.

The foreign ministry said "Moscow took note of the Syrian foreign ministry representative's statement" and then pointed out that Damascus had signed the 1925 Geneva protocol in 1968.

The ministry had earlier on Tuesday re-issued an earlier Syrian travel advisory warning to all Russian citizens.

Syria 'in control of chemical weapons': Israel
Jerusalem (AFP) July 24, 2012 - Syria's chemical weapons stockpile is under the control of President Bashar al-Assad's regime, Israel's armed forces chief said on Tuesday, while warning the arms could still reach hostile elements.

"As of this moment, Assad has control over the stockpiles," Lieutenant General Benny Gantz told members of the parliamentary foreign affairs and defence committee.

"They are increasing security over the weapons," he said.

"As far as we know, they have not yet passed into negative hands, but it doesn't mean it won't happen," he said, referring to Lebanon's Shiite Hezbollah militia and other radical groups operating in the region.

"They could use it against civilians or to transfer certain components of it to Hezbollah," he said in remarks relayed by a committee spokesman.

Similar assurances were given earlier on Tuesday by top defence ministry official Amos Gilad, who said Syria's stockpile of chemical weapons was "under the full control" of the Assad regime.

"The fear is that if the regime is shaken, its control will also be shaken," Gilad told public radio.

The Israeli officials' remarks came after Syrian rebels accused Assad of moving some of his chemical weapons to the border area.

"We also reveal that Assad has transferred some of these weapons and equipment for mixing chemical components to airports on the border," a rebel statement said.

Foreign Minister Avigdor Lieberman warned that Israel would consider the transfer of Syrian chemical weapons to Hezbollah a "casus belli" and would act "without hesitation or restraint."

"The moment we see the Syrians transferring chemical and biological weapons to Hezbollah, this is a red line for us," Lieberman told a Brussels news conference.

"From our point of view, it is a clear casus belli. We will act decisively and without hesitation or restraint," he said.

Lieberman's remarks join those of Defence Minister Ehud Barak, who on Sunday said: "The state of Israel cannot accept the transfer of advanced weapons systems from Syria to Lebanon," warning that such a scenario could spark an Israeli military response.

Asked about the possibility of pre-emptive military action, Gantz said it would not be easy and could spark a much broader conflict.

"If you want to work in a very focused way, it could be difficult to find the exact point," Gantz told MPs during the Tuesday session.

"And if you act broadly, you could quickly find yourself in a much bigger battle than you planned," he warned.

He said clashes between the Syrian army and rebel forces, focused around Damascus and Aleppo, had also reached the strategic Golan Heights plateau, part of which was occupied by Israel in the 1967 Six-Day War and later annexed.

"Battles are taking place before our eyes in the Golan area," he said.

"Yesterday three mortar rounds hit near the fence," he added, stressing they were not aimed at Israel.