RSS feedsBulmer brought in the firm, its current auditor, following the discovery of £3.3m in previously unaccounted expenses, understood to relate to promotional costs.
The news follows a shake-up in the company's senior management team and a disappointing performance in the UK take-home business last year.
In a statement, the comapny said: 'We are carrying out additional detailed work with our auditors to confirm this estimate and expect to report by the end of September.'
Bulmer, which produces Strongbow and Scrumpy Jack, had previously been audited by Andersen, but switched to Deloitte when the two firms merged last month.
There has been no suggestion the hole resulted from an auditing error.
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