Caterers have hit back over claims they are overcharging customers for the services of a shomer.

Last week, a JC investigation found that some caterers appeared to be marking up the cost of hiring a shomer - the person responsible for ensuring that food is prepared in accordance with kashrut laws.

The Kosher London Beth Din, which provides shomer services to more than 40 catering companies, acknowledged that it had received reports of customers being overcharged.

But some caterers have denied that the practice goes on, and instead criticised what they described as a lack of transparency in how kosher authorities set shomer fees.

Ben Tenenblat, who has 10 years' experience in the industry, three of them running his own firm, said: "I've never come across any overcharging. It's never come across my radar."

Every caterer has their own way of working

However, Mr Tenenblat, whose company is supervised by the KLBD, added that the current system was "very confusing".

Shomer fees are set by kashrut authorities using a formula taking into account the number of guests, the venue, the nature of the work and the preparation time required.

The authorities tell the caterer what the fee should be, and the caterer passes that cost onto the client.

However, because of variables such as extra preparation days or the need to work overtime, Mr Tenenblat said that it was "extremely hard to give an exact figure to a customer at the inquiry stage". He explained: "If someone books us a year in advance, given the current system of fees from the KLBD and the numerous factors to the event, it would be more or less impossible to give an accurate figure to the end client."

He continued: "The problem is if a client gets five different quotes. It's very confusing as to why I have made my calculations this way and another caterer has come up with it another way and that's why you're going to get five different figures."

One way of eradicating the confusion would be to simplify the fee structure, he said.

"We want a simple formula. So we can quickly say to the client, it's going to be x pounds per person, and it's all the same across the board, regardless of whether you're a high-end or low-end caterer, or what venue you're going to."

Tony Page, who has run his kosher catering company - supervised by the KLBD - for 25 years, also said he had "never come across" overcharging.

He described the idea of a simplified fee structure as "not impossible, but complicated".

He said: "Every caterer has their own way of working. Some will turn up on the day and do the work and just rely upon the shomer and the service in that one moment.

"Others will spend three or four days on preparation. That all has to be supervised and that will add to the costs, so it really depends on the caterer.

"The Beth Din may charge fees but it's determined by the venue that's worked in as well.

"Some are more complicated than others; some require two shomers. There's no formula where you can say 'this is the charge for this, that's the charge for that'. It's complicated and evolves and it is what it is."

Mr Page added that he had no issue with the way the Beth Din operated: "I have nothing but praise to heap upon the London Beth Din," he said.

"They do an amazing job and they give us a fantastic back-up and service."

Arieh Wagner has been running his kosher catering company for 19 years, with supervision provided by the Kashrut Authority of the Federation of Synagogues.

In a Facebook post, he strongly denied caterers inflated shomer fees.

"The notion that caterers make a killing out of trumped-up charges and put people off from going kosher is misleading," he said.

In an apparent swipe at the kosher authorities, Mr Wagner continued: "The main culprits are the communal organisations which, on one hand, turned the kashrut arm into a lucrative business and, on the other hand, whitewash themselves from all blame.

"We need the communal bodies for the kosher licensing but should they become profit centres? And should they deploy the caterers collecting and guaranteeing their fees?"

One caterer, who declined to be named, said there "was no science to the way fees are worked out". He said authorities should make fees public.

A spokesperson from the KLBD said that it was "always happy to advise" on the fees for any event. The spokesperson added: "There is a set formula through which kashrut fees are calculated which is the same for all caterers and is dependent on the number of people attending, venue, the nature of the work and the preparation time required.

"Therefore, a more complex menu will result in a different fee to a simpler event. We continue to look at different ways to make fees available to consumers."

The Federation Beth Din declined to comment.