Lafarge's move came minutes after the stock market closed and followed reports that RMC, another industry giant, had increased its stake in Ennemix to 5 per cent after buying more than 1 million shares in the market at Lafarge's new offer price.
Lafarge said its UK subsidiary Norbrit yesterday bought 618,500 Ennemix shares and now speaks for 49 per cent of the company. Dealers noted another active session in the shares, which closed 4p higher at 55p.
Derek Jenkins, RMC finance director, confirmed his company had been in the market buying Ennemix's shares for the third day running, though he thought RMC's stake in Ennemix now stood at "just over 2 per cent".
Dealers reckoned RMC's move was an attempt to prevent rival Lafarge acquiring the 90 per cent of Ennemix it requires to mop up the whole group.
But Mr Jenkins denied that RMC had sought to spoil Lafarge's previous, agreed, 46p per share bid for Ennemix by purchasing stock through broker James Capel at 50p.
"It is a strategic move," he insisted last night. "We won't make a bid for Ennemix." RMC plans to issue another statement to the Stock Exchange today.
RMC is the third large construction company to show an interest in the tiny East Anglian-based quarries group. In April, Ennemix defeated a hostile pounds 6.7m bid from Redland, the building materials group, which involved appeals to the Takeover Panel and disagreements about the valuations of Ennemix's nine quarries and 16 concrete plants.