The fight between BPB and French materials firm Saint-Gobain, which has launched a £3.6bn hostile takeover bid, raged on this week.

In its latest statement to the stock exchange on Friday, UK plasterboard firm BPB repeated its claim that Saint-Gobain’s offer undervalued the company.

It said its current share price of 736.5p, 16.5p above the offer price, substantiated chief executive Sir Ian Gibson’s view that the offer was too low.

The statement came after Saint- Gobain questioned figures in a document BPB sent to shareholders, urging them to reject the bid.

Saint-Gobain said the company “does not believe the methodology used by BPB is valid,” and stood by its offer price of 720p a share.