The US decision to postpone possible strikes on Syria has done little to allay fears in northern Israel, where queues at post offices were backing up as civilians collected gas masks.

Talk of imminent US military action against the regime in Damascus for its alleged use of chemical weapons had sparked widespread panic in Israel.

Fearing the fallout from any attack on Syria could spill across their northern border and drag the Jewish state into the conflict, Israelis last week rushed to replace their old gas masks.

US President Barack Obama's decision to ask Congress to authorise military action on Saturday lifted the threat of immediate strikes on President Bashar al-Assad's government.

But queues continued to back up for hours as many Israelis, particularly in the north near the borders with Syria and Lebanon, insisted on collecting protective gear that has been distributed at post offices across the country.

Local media reported on Monday that some 40 percent of the population still did not have gas masks.

"We've already had missiles in the north," said Dalia Eliahu, who queued in a distribution centre in a park near the northern coastal town of Haifa, which is about 70 kilometres (43 miles) from the Syrian border at its closest point.

She was referring to attacks on northern Israel by Hezbollah in a month-long war in 2006, and to an August 22 attack launched this year from southern Lebanon that saw four rockets fired without causing casualties or damage.

"But this time, if Assad sends missiles with chemical (warheads), we can't take it lightly," said Eliahu, a recent retiree.

Yann Lukatzki, 35, had also been waiting for five hours in the public park to pick up his mask from a distribution point.

"We shouldn't hesitate to come and pick up our masks," he told AFP.

"The international community must intervene. It's immoral to leave this tyrant (Syrian President Bashar al-Assad) in place, but his retaliation could affect us, so we must be ready for all eventualities," Lukatzki said.

Israeli Prime Minister Benjamin Netanyahu said Sunday that the Jewish state was prepared for "every possible scenario" in neighbouring Syria after US President Barack Obama postponed a threatened missile strike.

And it is Israelis in the north who need the most reassurance.

The July 2006 33-day war against Lebanese Shiite movement Hezbollah, which supports Assad, saw thousands of missiles fired over the border.

The conflict killed some 1,200 Lebanese, mostly civilians, and nearly 160 Israelis, most of them troops.

Avi Ohana, a 47-year-old engineer, told AFP "we can't wait till the last moment" to prepare gas masks.

There was brief tension in the park in Haifa as distribution was postponed until the next day.

"We've queued for two hours for nothing," pointed out Avraham Mor Yossef, an ultra-Orthodox Jew from a village on the Israeli-Lebanese border.

"I have three children who haven't got their masks, and I can't miss another day of work to pick one up," he pleaded with a local policeman.

Newspaper Maariv said a centre in Jerusalem was forced to close last Wednesday after anxious residents grabbed all the mask kits on the premises.

But even in the north, some were more philosophical.

"Assad won't try and attack us," said Cyril Kleczewski, an engineer. "He knows he'd be signing his own death warrant" -- an allusion to Israel's own retaliation should it be targeted.

Gas masks were first distributed to the general public during the 1991 Gulf War over Kuwait when Saddam Hussein's Iraq fired 39 Scud missiles at Israel as the US-led coalition launched Operation Desert Storm.

Israeli experts have said that the danger of a similar attack by the regime of Syria's President Bashar al-Assad or its Lebanese proxies Hezbollah was low.