The alleged 鈥渇inancial irregularities鈥� that led to 128 redundancies at Alfred McAlpine鈥檚 Welsh Slate subsidiary this year referred to products sold at half their break-even price, it has emerged.

It was known that the misrepresentation of sales and production volumes were behind McAlpine鈥檚 decision to sack senior managers and close a quarry in Blaenau Ffestiniog. However, the details were not known.

A source said McAlpine had concluded that managers initially underpriced the slate, then issued invoices that overstated the amount sold so turnover targets could be met. It is also believed that managers discounted slate in return for a quick cash sale.

It is thought McAlpine will take a 拢40m hit as a result of the underpricing.

Events at the quarry are being investigated by police, although it is not though that managers benefited individually.

The source added that the police investigation into the incident would not be completed for 鈥渕onths or years鈥�.

Alan Smith, interim manager of McAlpine鈥檚 slate division, said the company was in talks to sublet the quarry to a local stone supplier.