Jean-Pierre Cuny, chief executive of plasterboard giant BPB, has stood down in the wake of a European Commission investigation into the company. In a shock move, Cuny, 58, who has been with BPB for 21 years, announced on Wednesday that he is to stand down.

A BPB statement said: "The board and Mr Cuny have agreed that, in the light of the current investigation into the alleged infringement of Article 85 of the Treaty of Rome within the European gypsum industry, it would be appropriate for a new CEO to take the group forward." Commission investigators probing an alleged cartel in the industry swooped on BPB's offices in Slough, Berkshire, in late November (4 December 1998).

Rival manufacturers Lafarge and Knauf are also being investigated. Officials said the investigation began after a tip-off about an alleged breach of the Treaty of Rome.

BPB said it has accepted an offer from Cuny to assist the company in dealing with the investigation, and he will be kept on as a consultant throughout the inquiry.

Cuny has been succeeded by 60-year-old David Leonard.

After the announcement, BPB's shares dropped 3.9% to 189p on Wednesday. This follows a 20% drop in share value after the raids in November.