LONDON (AP) — U.K. grocery chain Sainsbury's has confirmed it is in advanced discussions about a merger with Walmart Inc.'s British unit, Asda. 

The combination would create Britain's largest supermarket chain, moving the merged company ahead of market leader Tesco. J Sainsbury plc, the chain's corporate name, released no other information on Saturday and said it would make an announcement before the London stock market opens on Monday.

The move underscores the intense competition in Britain's grocery market as discounters like Asda take market share from traditional chains such as Sainsbury's and Tesco.

Kantar Worldpanel, a retail research firm, puts Tesco's market share at 27.6 percent, followed by Sainsbury's at 15.8 percent and Asda at 15.6 percent.

The merger was first reported Saturday by Sky News.