The chief executive of Casino has called for a meeting with its fellow shareholder in CBD to discuss the controversial plan to merge the Brazilian retailer with Carrefour's local unit.

Jean-Charles Naouri has asked Abilio Diniz, the head of the Diniz Group that co-owns CBD with Casino, to discuss the proposal, which the French retailer has labelled as "illegal" and hostile".

Yesterday (28 June), after weeks of speculation and reports of talks between Diniz and Carrefour over a possible deal on CBD, Brazilian investment fund Gama put forward a merger proposal.

Under the plan, the fund and CBD would merge. CBD would then be combined with Carrefour's Brazilian subsidiary, therefore holding all of the subsidiary's shares. Gama would then give Carrefour 50% of the combined business in return for an 11.7% stake in the world's second-largest retailer.

After the speculation of talks between Diniz and Carrefour first emerged last month, Casino filed for arbitration at the International Chamber of Commerce. Casino said Diniz had to comply with a 2006 shareholders deal that meant its fellow shareholder could not hold talks over the future of CBD without involving the French retailer.

Since then, a French court has claimed that raids on Carrefour's HQ provided evidence that the retailer did hold talks with Diniz over CBD.

Casino and Diniz control CBD through a holding company called Wilkes. However, Casino claims that in 2005 it acquired the right from Diniz to become the sole shareholder in CBD in 2012.

In a letter to the CBD board and its CEO Enéas Pestana yesterday, Naouri said he had requested that Diniz, in his capacity as Wilkes chairman, "immediately" holds a meeting to discuss the Gama proposal.

Naouri said no deal could be made without the "required approval from the controlling shareholder Wilkes."

He said: "We deeply regret that, as publicly disclosed and now confirmed by the proposal, Mr Abilio dos Santos Diniz, who has already sold and received the consideration for [CBD's] control in 2005, initiated and conducted secret and unlawful negotiations with a third-party competitor of the company and its representatives without even informing the single largest shareholder of the company and whilst publicly denying the existence of material negotiations.

"We stress that, in light of an aggression of this magnitude, we will not hesitate to continue the pursuit of any appropriate measures for the protection of the interests of the company and all of it shareholders, as well as of the rule of law and of the respect for private property that characterise Brazil."

Naouri added that Casino had an "irreversible commitment" towards CBD. Two weeks ago, amid the speculation, Casino upped its stake in the retailer from 33.7% to 37%.