A former Wal-Mart Stores Inc. worker said he was part of a large surveillance operation that included snooping on employees, stockholders and others, according to a Wall Street Journal report Wednesday.

Security worker Bruce Gabbard was fired last month after 19 years with the company for intercepting a reporter's phone calls, the paper said.

Gabbard said he recorded the calls because he felt pressured to stop embarrassing leaks. But he said his spying activities were sanctioned by superiors.

Gabbard said that as part of the surveillance, the retailer infiltrated an anti-Wal-Mart group to determine if it planned protests at the company's annual meeting last year and deployed monitoring systems to record the actions of anyone connected to its global computer network.

Many of Gabbard's statements were confirmed by other former Wal-Mart employees, the paper said.