Casino plans to oppose any potential deal to merge Brazilian retailer CBD - in which it is a shareholder - with Carrefour's local operations.

Carrefour this morning (28 June) announced that it has received an offer to join forces with CBD in a move that would scupper any attempts by Casino to gain more control over the Brazilian retailer.

This latest proposal, received from investment fund Gama and backed by the Brazilian National Development Bank (BNDB), will merge Carrefour's Brazilian assets with those of CBD, in an equally-owned joint-venture.

Casino holds a 37% stake in CBD, also known through its trading name as Grupo Pao de Acucar. Earlier this month, the French retailer increased its stake in CBD to 33.7% amid reports that the Brazilian company and its second main shareholder, the Diniz family, had been in talks with Carrefour. The rumours also prompted Casino to file for arbitration against the Diniz family.

In a statement today, Casino said that contrary to the terms outlined by Carrefour this morning, the proposal from Gama is not spontaneous but "a long-standing, illegal, planned financial transaction".

"This announcement confirms that illegal and secret negotiations were conducted and are ongoing," the statement said. "Indeed, in consideration of the public agreements Casino signed with Abilio Diniz [the head of the Diniz family], no negotiations involving the future of CBD can occur without Casino."

Last week, it emerged in court in France that raids of Carrefour's HQ by bailiffs and IT experts had found documents that established that there had been talks between the retailer and CBD.

Casino claimed that, despite reminders to Diniz and Carrefour of the obligations under the agreement between the two shareholders in CBD, discussions have continued, "deliberately ignoring both the law and fundamental business ethics".

The retailer said it will "examine how to best defend the corporate interests of CBD and its shareholders", over the next few days.

"Casino recalls that it has the authority to oppose this project according to the existing agreements and that no negotiations regarding the future of CBD can be conducted without its consent and without prior discussion of this project at the board of directors of Wilkes, the holding company controlling CBD," it added.