The president of the London Board for Shechita has warned that a new meat operation launched by the Federation of Synagogues could threaten the future of kosher beef in Britain.
Benjamin Mire said the initiative could result in the closure of the LBS's cattle abattoirs in Manchester.
That could be the "catalyst for the demise of cattle shechita within the UK", he said. The Federation's move was "incredibly unhelpful to the preservation of shechita in the UK".
The Federation is one of the three partners - along with the United Synagogue and the Spanish and Portuguese Jews Congregation - in the Board, which licenses kosher meat in the capital
The Federation has rejected claims that its scheme, aimed at the strictly Orthodox market, conflicted with the LBS and said that competition benefited consumers.
As frantic negotiations took place this week to avert a split, a LBS source said: "Every effort is being made to try and establish some common ground".
Mr Mire wrote to Federation president, Andrew Cohen, last week to express "shock" at hearing that the Federation had slaughtered beef in an Irish abattoir and given a licence to Gilberts, one of the LBS's main licensees, to supply it.
It seemed "quite contrary" for the Federation to participate in a cross-communal body, Mr Mire wrote, and to "conduct its own separate shechita operation outside the parameters of the London Board and clearly now in competition and in conflict with an organisation of which it remains part".
Last month the LBS rejected a proposal from the Federation to launch a new mehadrin range of meat - mehadrin requiring stricter supervision than standard kosher meat.
The Federation made clear that it wanted to offer an alternative to Kedassia, the kashrut arm of the Union of Orthodox Hebrew Congregations.
The first consignment of Federation mehadrin meat arrived at the Kosher Outlet store in London on Wednesday.
Professor David Rosen, the Federation's legal adviser, said this week that it saw "a change in market demands and we have reacted to a growing number of people who want to be additionally strict in line with the teachings and customs of their rabbonim, which is not currently catered for by the LBS. That does not diminish or detract from the standard or quality of the hechsher [kosher certificate] of the LBS".
Competition was "good for the consumer", he said.
The Federation wanted to continue its association with the LBS, he added, and was "hopeful that constructive discussions will take place with the LBS to reach a mutually amicable solution".
Mr Mire told the Federation last month that the LBS's other partners, the US and the Sephardim, were against the mehadrin plan as presented.
The LBS felt the mehadrin range could cause confusion among consumers and imply that the kashrut quality of its existing brands were "below par", he explained. As well as standard meat, the LBS also offers options for consumers who seek a stricter level of supervision.
There was also "unease", he said, at the aim to "take business" from Kedassia.
Mr Mire said he was shocked last week when the LBS received an email from Norman Bookbinder, director of Gilberts, "purporting to terminate his licence" with the LBS.
Gilberts was the largest buyer of meat from the LBS's cattle abattoirs in Manchester, Mr Mire wrote. If those purchases disappeared, there was "real concern that the abattoirs' operation may become unviable, and they may decide to withdraw from the shechita market".
Mr Bookbinder, who met the LBS on Monday, was unavailable for comment.
The Federation had told the LBS that the Kosher Outlet sold around £1 million of Kedassia meat last year but that the mehadrin brand would be cheaper.
During correspondence, it emerged that one shochet employed by the LBS earns a salary "in excess of £100,000".