Syrian President Bashar Assad's regime has taken precautions to avoid chemical weapons falling into rebel hands, a senior Israeli official said Monday.

"He is handling chemical weapons responsibly" despite the pressure he is under, the official said. Assad has been moving some of the chemical stockpiles to bases remote from the fighting or having greater security, the source added.

Experts say that to adapt the chemical warfare materiel for military use, a number of steps are required, such as mixing several chemical substances together, and installing special fuses on artillery shells and bombs on aircraft. Without the fuses it is impossible to use the shells and bombs effectively.

Loading the chemical substances on rocket and missile warheads is another process.

On Monday, Israel continued sending diplomatic and other messages about its concern over the possibility that Syria's chemical weapons could fall into Hezbollah's hands, and about the preparations for a military operation to prevent it.

Foreign Minister Avigdor Lieberman, who met France and Britain's foreign ministers in Brussels, told them any attempt to move chemical weapons from Syria to Hezbollah would be "crossing a red line" as far as Israel is concerned.

"We won't restrict ourselves and will respond very harshly if this happens," Lieberman said.

President Shimon Peres spoke about the issue in an interview with CNN.

"If the alternative is to be killed or to prevent, there is only one alternative: to prevent," Peres said. "Israel cannot remain unconcerned over the transfer of chemical weapons that may be pointed at her."

The senior Israeli official said at this stage there are no signs that Assad has moved or intends to move chemical weapons to Hezbollah, but is making moves to keep the weapons out of rebel hands and away from organizations identified with Al-Qaida.

"However, Israel is still very concerned because it is hard to know if these steps will be sufficient on the day Assad falls," he said.

Syria's Foreign Ministry spokesman Jihad Makdissi held a press conference in Damascus on Monday focusing on the international concern over Syria's chemical weapons.

Syria will not use the weapons against its own people, he said. "Any chemical or bacterial weapon will never be used - and I repeat will never be used - during the crisis in Syria regardless of the developments," he said.

"All of these types of weapons are in storage and under security and the direct supervision of the Syrian armed forces and will never be used unless Syria is exposed to external aggression," added Makdissi.

The United States has warned Syria against using the arsenal under any circumstances.