JERUSALEM: Israel is increasingly worried that Syrian chemical weapons could fall into the hands of Islamist militants and is taking military and diplomatic steps to prevent it, local media and a security source said Monday.

Two batteries of Israel's Iron Dome missile defence system have been deployed to the north of the country in case military action against targets in neighbouring Syria or Lebanon becomes necessary, a security source told AFP on condition of anonymity.

He said Israel believes Lebanon's Hezbollah has a large number of forces in Syria that are supporting President Bashar al-Assad against Sunni rebels, but which are also keen to grab his chemical weapons if he falls.

"A decision to attack in Syria or Lebanon will need to be implemented immediately," if it is taken, he said.

"There won't be time then to start deploying."

The Israeli army played down its manoeuvres, saying that only one battery had been moved north.

"As part of the operational deployment programme, which includes changing locations throughout Israel from time to time, (an) Iron Dome battery is currently in the north," it said.

The Maariv daily said that Prime Minister Benjamin Netanyahu had "urgently dispatched" his national security adviser to Moscow, where he will meet Russian Foreign Minister Sergei Lavrov.

He is expected to ask the Russians to use their influence to try to prevent the weapons from falling out of Assad's control.

The newspaper said that Netanyahu met US ambassador to Israel Dan Shapiro on Sunday. Shapiro said on Monday that the two countries were closely coordinating on events in Syria.

"There is a genuine discussion between our intelligence services," he told Israeli public radio.

"There are two dangerous possibilities," he said. "Either the regime will use chemical weapons against the Syrian people or the chemical weapons will pass to Hezbollah or to other extremist organisations."

"We want to prevent both those possibilities taking place."

Witnesses in northern Israel reported intense Israeli air force surveillance over Syria and Home Front Defence Minister Avi Dichter said the Jewish state was watching events in its neighbour closely.

"Israel, and not only Israel, is keeping an eye, a very close eye, and trying to understand in the most precise way possible what is happening to the (weapons) stockpiles," he told public radio.

"It's a problem that has to be dealt with from two aspects," he added.

"One is how to reduce what is (stockpiled) and the other is how to deter anyone intending to get his hand on it, to let them know that their hand will be badly burned if they even think about it, certainly if we're talking about terror organisations."

Cabinet colleague Benny Begin said Israel was already preparing for the day after Assad.

"It looks like Syria will fragment into smaller sections and there will be a measure of anarchy there for some time after the fall of Assad," he told army radio.

"We have to prepare for what lies in store, and there is a responsible government doing just that."

According to Israeli media reports, Netanyahu on Wednesday convened an emergency discussion with the security establishment and his inner cabinet on the situation in Syria and the risk of it losing control of chemical weapons.