Britain's Competition and Market Authority (CMA) said in a statement on Friday that it has issued a preliminary “invitation to comment” asking all interested parties to submit initial views on the impact the deal could have on competition by June 4.
The regulator said it is also likely to contact companies in markets affected by the proposed merger, or that have "valuable insights or evidence that could assist the CMA's investigation, such as suppliers, competitors, industry bodies and consumer organisations”.
“The CMA is keen to ensure that all interested parties have the opportunity to make their views known and present all relevant evidence to the CMA,” it said.
It is also looking to send out a consumer survey to hear customers' thoughts about the deal.
Some analysts have said they expect the two supermarkets will be asked to sell stores to get the go-ahead from the CMA.
David Haywood, founder of Maximise UK – a specialist in identifying new locations for retail stores – believes at least 6% or 73 of the enlarged group’s supermarkets are at risk, excluding convenience stores.