Syria's alliance with Iran and Lebanon's Hezbollah took "a severe blow" after a deadly rebel attack on Damascus killed three top security chiefs, Israeli Defence Minister Ehud Barak said on Thursday.

He said the bombing was "a severe blow to the radical axis, to the Iranians and Hezbollah, who are the sole supporters of the Assad family", he said in remarks communicated by his spokesman.

The minister said it was possible to watch the battle playing out less than a kilometre away in the Syrian village of Jebata al-Khashab.

"We can see the actual fighting, the mortars, hear the bullets between the Syrian army to rebels or the opposition," he said.

"This shows how the disintegration [of the Assad regime] is not abstract. It is real, it's approaching and what happened yesterday in Damascus will expedite the downfall of the Assad family," he said.

Barak noted growing audacity of rebels and said the Assad family's hold on Syria was "falling apart in front of our eyes" warning that no-one knew what would remain afterwards.

Also on Thursday, Syrian National Council spokesman George Sabra said: "We see that what happened is a sign of the beginning of the end of the regime". [AFP]