Switzerland's competition and monopolies agency Comco has launched a probe into Coop's planned acquisition of Carrefour's stake in retailer Distributis AG.

The investigation comes amid concerns that the move may breach competition laws.

In August, Carrefour and Maus Frères agreed to sell their respective stakes in Distributis AG to Coop for an equity value of CHF470m (EUR287m).

The venture Distributis AG, 50% owned by Carrefour and 50% owned by its partner Maus, operates from 12 hypermarkets.

"We do have a high concentration in the food retail markets - as is the case in the UK or Finland," said Patrick Krauskopf, Comco's vice-director .

"If the number one or two player takes over a competitor, Comco is supposed to look more closely at the transaction.

"We have concerns about the joint dominance of the two largest retailers and we have to have a closer look at the buying power that arises out of such a merger."