BENTONVILLE, Ark. — Walmart Stores Inc. has alerted its global suppliers that it will immediately drop them if they subcontract their work to factories that haven’t been authorized by the discounter.

Wal-Mart’s stricter measure, along with other changes to its policy, comes amid increasing calls for better safety oversight after a deadly fire at a Bangladesh factory that supplied clothing to Walmart and other retailers. The fire in late November killed 112 workers at a factory owned by Tazreen Fashions Ltd. Walmart has said the factory wasn’t authorized to make its clothes.

In a letter sent Tuesday to suppliers of its Walmart stores as well as Sam’s Clubs in the U.S., Canada and the United Kingdom, the company says it will adopt a “zero tolerance” policy on subcontracting without the company’s knowledge, effective March 1. Previously, suppliers had three chances to rectify mistakes.

Walmart also said it plans to publish on its corporate website a list of factories that haven’t been authorized to manufacture goods for Walmart.

Also, starting June 1, suppliers must have an employee stationed in countries where they subcontract to ensure compliance, rather than relying on third-party agents.

“We want the right accountability and ownership to be in the hands of the suppliers,” said Rajan Kamalanathan, Walmart’s vice president of ethical sourcing. “We are placing our orders in good faith.”

Walmart will be holding a meeting for clothing suppliers from the U.S. and Canada on Thursday to explain the new policy changes.

Walmart ranks second behind Swedish fast fashion retailer H&M in the number of clothing orders it places in Bangladesh.

Before the fatal fire there, Walmart had taken new steps to address the growing problem of safety such as mandating fire safety training for all levels of factory management.