The CCPC said that following an extended preliminary investigation, it has determined that a full investigation is required in order to establish if the proposed transaction could lead to a substantial lessening of competition in the state.

“The CCPC will publish its Phase 1 determination no later than 60 working days after the date of the determination and after allowing the parties the opportunity to request that confidential information be removed from the published version,” it said.

The supermarkets currently operate under the Joyce family’s independent brand and will be rebranded and designed as Tesco stores on a phased basis, if the deal gets the go-ahead.

Joyce’s staff will also become Tesco Ireland employees if the deal completes.

Patrick C Joyce started the family business in Headford in 1951 with a small grocery store and then developed into a general supermarket. Pat Joyce took over the business in 1988 and since then nine more supermarkets have been opened in Knocknacarra, Athenry, Tuam, Inverin, Ballybane, Fr Griffin Road, Doughiska, Oranmore and Oughterard. The group employs more than 500 people.

Tesco Ireland has 151 stores nationwide and five in Galway and employs over 13,000 people in cities and towns around Ireland.