Ray O’Rourke, the chairman of Laing O’Rourke, has decided to write to all the firm’s major customers before he attends an employment tribunal for the apparent unfair dismissal of a former senior member of staff.

Neels Kriek, formerly managing director of Integrated Solutions for Laing O’Rourke’s European business operations, is hoping to be successful in his claim for unfair dismissal and hopes that a compensation packet be rewarded to him. As well as wrongful dismissal he has accused Laing O’Rourke of cheating the NHS of money.

O’Rourke took the unusual step by writing to his clients to tell them about the allegations at the end of June: “The claimant claims his dismissal was a result of having allegedly made disclosures on unlawful practices relating to commercial activities in parts of our business, which he claims to have brought to the direct attention of the European board.

Those accusations are: that we failed to declare the cost savings of central supplier rebates when we were required to under the terms of a Procure 21 framework agreement with the NHS; [and] that there were irregularities in the way the group managed main contractor discounts.

We were not, and never have been engaged in any unlawful practices relating to these issues. Further we can find no evidence that the claimant brought these allegations to our attention prior to discussions with him regarding his departure, which was a direct consequence of the disbanding of the business unit he headed.”

A source at Laing O’Rourke said the NHS had been made aware of the allegations and had given it “a clean bill of health”. A spokesman for Laing O’Rourke said it had “vigorously defended” the allegation.

Kriek had hoped that his claim could be heard under “whistleblowing regulations”, but the tribunal last week decided that the disclosures did not fall within whistleblowing laws.