TOKYO (Kyodo) -- Japan's antitrust watchdog on Tuesday searched three major refrigeration equipment manufacturers on suspicion of rigging bids for frozen and refrigerated display cases ordered by convenience store operator Seven-Eleven Japan Co., sources close to the matter said.

The Japan Fair Trade Commission conducted on-site inspections of Fuji Electric Co., SDRS Inc. and Nakano Refrigerators Co. for possibly violating the antimonopoly law.

Convenience stores install large numbers of refrigerated display cases for soft drinks, frozen foods and other items. If the companies colluded to inflate prices, it could have squeezed the business of not only Seven-Eleven Japan, which awards the contracts, but also franchise operators that lease the equipment.

When questioned by reporters, all three companies acknowledged the inspections and said they would fully cooperate with the investigation.

The three companies are suspected of deciding in advance which firm would win bids for in-store display cases ordered by Seven-Eleven Japan by coordinating price quotations beforehand.

Bids are held once every few years on a prefecture-by-prefecture basis, and the winning firm is believed to handle not only delivery of the equipment but also maintenance checks and other services.

According to the Japan Refrigeration and Air Conditioning Industry Association, domestic shipments of frozen and refrigerated display cases in fiscal 2025 totaled 256,475 units. This is about 17 percent down from a decade earlier, suggesting that the firms may have sought to maintain or expand sales by avoiding competition.

Fuji Electric's website said the company has a domestic market share of over 40 percent for convenience store display cases.

Meanwhile, the financial statements for the year ended December 2024 for Nakano Refrigerators, which also focuses on the display case business, showed that transactions with Seven-Eleven Japan accounted for around a quarter of its sales.