As the festival of Chanucah approaches, Israelis are being warned to watch out for a particular seasonal hazard: fake olive oil.

Leading kashrut expert Rabbi Yosef Zaritsky told shoppers on the Charedi website Bchadrei Charedim that those buying oil for Chanucah, which starts on Friday night, should “be on guard for counterfeit oil”.

Officials from the Chief Rabbinate are also engaged in a campaign against brands that emerge during the holiday season selling cheap olive oil that is of questionable content.

“Fraudulent kosher seals and fraudulent olive oil often go together,” says Rabbi Rafi Yochai, the chief kashrut enforcer for the Chief Rabbinate.

“Oil fraud has been carried out on a vast scale in the past but we are fighting the phenomenon and raising public awareness of it.”

Rabbi Zaritsky said that the market has been infiltrated by merchants engaging in “foilishtik”, or foolishness, by mixing in flavouring and smell additives. In some cases they mix soya oil with the olive oil.

He said there were also cases of merchants adding colouring to soya oil to make it look like olive oil.

“Good olive oil is a function of price,” he says. “It should cost at least NIS 35-40 [£5.50-6.50] a litre, and if not, it is not olive oil.”

He recommends spreading oil on one’s hand to test whether it is pure olive oil.

“If after five minutes, the smell remains, then it isn’t olive oil. The smell of olive oil dissipates.”

Store owners selling oil at more expensive stores at Jerusalem’s Machaneh Yehudah market on Wednesday tended to enthusiastically agree with Rabbi Zaritsky’s warning.

But a staffer at the Rosemarin store, whose oils included a bottle for just NIS 20, called it “not very precise”.

Another store featured a bottle of olive oil at only NIS 17.50. It had a picture on the label of the arch of Titus, an ancient oil lamp and olive branches with black olives.

Only on close inspection does it become clear the bottle contains not only olive oil but also vegetable oil. There was no brand name but the manufacturer was listed, again in small letters, as System Investments.

But maybe it is the purity of one’s intention and not the oil that matters, after all.

At an Ethiopian spice shop in Machaneh Yehudah, across from a fish store displaying pink salmon steaks, Fasika Kasa, who immigrated from Gondar in 1991, agreed that “good oil has to cost at least NIS 35”.

What if someone cannot afford it?

“Then they should light candles,” at NIS 4 a box.

“God knows from your heart what you can afford,” she said.

“If you don’t have the money, you don’t have it.

“The main thing is not to forget the holiday and to celebrate with whatever means you have.”