The Competition and Markets Authority (CMA) will examine whether the deal results in a substantial lessening of competition.
In a statement, the CMA said, 'The CMA is investigating the completed acquisition by Wm Morrison Supermarkets Ltd of certain assets of Mccoll’s Retail Group Plc, Martin McColl Limited, Clark Retail Limited, Dillons Stores Limited, Smile Stores Limited, Charnwait Management Limited, and Martin Retail Group Limited.'
Earlier this month, Morrisons, which has a wholesale supply deal with McColl's, took on all its 1,160 stores, including 270 Morrisons Daily branded stores, in a so-called pre-pack administration.
“Although we are disappointed that the business was put into administration, we believe this is a good outcome for McColl’s and all its stakeholders," said Morrisons CEO David Potts said at the time.
"This transaction offers stability and continuity for the McColl’s business and, in particular, a better outcome for its colleagues and pensioners."
Morrisons, which trails market leader Tesco, Sainsbury's and Asda, has been owned since October by U.S. private equity group Clayton, Dubilier & Rice (CD&R).
McColl's went into administration at the start of May with debt of just under £170 million (€198.8 million).