The head of LVMH, Bernard Arnault announced he had bought 17% of his rival Hermes, insisting that this does not herald a hostile takeover but that he simply wanted to become a "friendly" long-term shareholder.
"If you want to be friendly, Mr Arnault, you should withdraw," retorted Hermes executives Bertrand Puech and Patrick Thomas, in an interview with Wednesday's edition of French daily Le Figaro.
The pair alleged Arnault's tactics in taking the stake were questionable and said they hoped the financial services watchdog would investigate.
Puech is a fifth-generation heir of Hermes' founder Emile Hermes, while Thomas is the family owned firm's manager. Family members still control the 73% of the firm not in LVMH chief executive and chairman Arnault's hands.
LVMH, or Louis-Vuitton Moet Hennessy, is a French holding company and the world's largest luxury goods group, specialising in wines and spirits, fashion and leather goods, perfumes, watches and jewelry.
It owns more than 50 global brands, including marques such as Christian Dior perfumes, Glenmorangie whisky, Givenchy fashion and TAG Hauer watches.
The group made a €1.1bn profit in the first quarter, up 53% on the year with sales up 16% €9bn.
Hermes is a French fashion house that has branched into perfume and luxury goods. Smaller than LVMH, it nonetheless also saw profits up 55% in the first quarter on sales of €1.07bn.
The luxury goods industry has seen much consolidation in recent years, and there has been speculation about the fate of Hermes since the death in May of its charismatic former manager Jean-Louis Dumas.