Israeli soldiers treated "wounded" civilians on Tuesday in a simulated chemical weapons attack as part of an annual civil defence drill, against the backdrop of tension on its borders with Syria and an increasingly unstable Lebanon.

In the city of Holon, south of Tel Aviv, 150 troops evacuated civilians to a field hospital set up in a sports stadium and "contained" the area, simulating a chemical warhead attack, an army spokeswoman told AFP.

Soldiers also showered down comrades as if they had been exposed to toxic agents, at a water park converted into an emergency centre for the exercise.

During the drill, which began on Sunday and is to finish on Wednesday, the army tested its alert system, sounding sirens in civilian areas and using the Internet, mobile phone messaging, TV local radio to put out warnings of an "attack."

Schools were evacuated, and families were instructed to rush from their homes to the nearest shelter, as they would during a real attack.

This year, the exercise focused specifically on the threat of unconventional weapons, high-ranking military officers said.

"This exercise is set up to prepare for emergencies such as attacks of hundreds of missiles per day, missiles tipped with chemical warheads," General Eyal Eisenberg, chief of home front defence, said on Monday.

Israel has warned that Syria's chemical weapons arsenal could fall into the wrong hands and has carried out several air raids inside Syria on convoys it says were delivering arms to its arch-foe and Damascus ally, the Lebanese Shiite militant movement Hezbollah.

Last week an Israeli army patrol in the Golan Heights came under fire from Syrian regime forces located across the border in the disputed territory.

It was the latest of a number of incidents in Israeli-occupied Golan in the past few months that have included explosions of stray shells and small-arms fire from Syria.

"Our enemies won't try in the next war to conquer Israeli territory, but will fire missiles at civilian targets," Home Front Defence Minister Gilad Erdan said as he inspected a school.

But both he and Defence Minster Moshe Yaalon played down the risk of a chemical attack from Syria.

"We do not see anyone who is about to try and test us in the area of unconventional attacks in the foreseeable future," Yaalon told a news conference on Tuesday.

"The Syrian regime... is deterred by us," Yaalon said.

And Erdan told Israeli television on Saturday: "This is a scenario that is more probable than in the past, but the use of chemical weapons is still defined as a low probability even taking into consideration the fall of the (President Bashar al-) Assad regime."

"Our enemies know that the use of chemical or non-conventional weapons at the citizens of Israel will provoke a harsh and destructive response," he warned.

Israel fought a devastating war in 2006 with Hezbollah during which the Jewish state's arch-foe fired thousands of missiles over the border.

The 34-day war devastated parts of Lebanon and killed 1,200 people there, mainly civilians. Sixty Israelis -- 41 civilians and 19 soldiers -- died.

Israel boosted security measures after launching its air strikes in Syria, deploying two batteries of the Iron Dome missile defence system to the north.

The Syrian conflict has repeatedly spilled over into neighbouring Lebanon.

Two rockets hit Hezbollah's heartland in Beirut on Sunday, and 31 people were killed in the preceding week in the northern port city Tripoli in clashes between supporters and opponents of the Syrian regime.

"The threats against the Israeli home front have significantly increased in recent years," Prime Minister Benjamin Netanyahu said on Sunday.

"Israel is the most threatened state in the world; it is under missile and rocket threat. We are prepared for any scenario," he said.

The drill, the seventh of its kind, encompassed the army's home front command, the defence ministry, government bodies, municipalities and local authorities, rescue organisations and school systems.