(Adds comment from Walmart on signing of separation papers)
WILMINGTON, Del., June 7 (Reuters) - Walmart Inc has asked a court to block a former top tax executive from joining Amazon.com Inc, saying the move would violate a non-compete agreement and irreparably harm Walmart by potentially tipping off its rival to strategic plans including potential merger targets.
Lisa Wadlin told Walmart in January she was considering resigning as senior vice president, chief tax officer, but the company did not learn she was joining Amazon until separation papers were signed on May 15, according to the lawsuit.
Walmart clarified to Reuters that the retailer sent Wadlin a signed version of her separation agreement on May 15, but she never signed it.
Walmart, the world's largest retailer, said Wadlin's knowledge of its strategic plans "would be of immense benefit to Amazon," according to the lawsuit, which was filed late on Wednesday in Delaware's Court of Chancery.
Walmart spokesman Randy Hargrove said senior executives at Walmart agree to forgo working for competitors with revenue in excess of $7 billion for two years after leaving the company.
"We believe Ms. Wadlin's acceptance of a job with Amazon will violate her non-compete clause," Hargrove said.
Wadlin and Amazon did not immediately respond to requests seeking comment.
Walmart has been plowing money into its online business to try to keep pace with Amazon, which has muscled its way into the brick-and-mortar grocery business with its acquisition of Whole Foods.
Wadlin was hired by Seattle-based Amazon as a vice president of tax and tax policy, according to the lawsuit.
She brings with her non-public information including insight into Walmart's potential merger targets, according to the lawsuit. The Bentonville, Arkansas-based company said Amazon could use that information to thwart Walmart's deals, or force it to pay more.
Walmart is seeking a court order to enforce the non-compete agreement, according to the lawsuit. It also wants the court to bar her from using or sharing confidential company information. (Reporting by Tom Hals in Wilmington, Delaware; Additional reporting by Nandita Bose in New York and Jeffrey Dastin in San Francisco; Editing by David Gregorio and Peter Cooney)