PYEONGTAEK, South Korea (AP) — Thousands of Samsung Electronics workers rallied Thursday at its computer chip complex in Pyeongtaek, South Korea, demanding higher bonuses and threatening to strike as booming demand for artificial intelligence drives up memory-chip profits.

Holding signs and waving banners, the workers gathered at a factory compound amid a heavy police presence, shouting “make compensation transparent and remove maximum limits on bonuses!” Union officials said about 40,000 members participated in the protest. Police did not immediately provide a crowd estimate.

The rally came hours after Samsung’s cross-town rival, SK Hynix, posted an all time high in quarterly revenue and operating profit for the January-March quarter, a jump it attributed to expanding global investments in data centers and other AI infrastructure that drove up the demands for its memory chips.

Samsung, which together with SK Hynix produces about two-thirds of global memory chips, forecast earlier this month that its first-quarter operating profit would reach a record 57.2 trillion won ($38.6 billion). That would be higher than the 37.6 trillion won ($25.4 billion) posted by SK Hynix on Thursday, although Samsung has a more diverse lineup of businesses, including smartphones and consumer electronics.

Samsung’s union, which represents about 74,000 workers, says the company has failed to offer adequate compensation despite its strong performance. It has rejected the management’s proposal for bonuses of restricted stock and calling for removing caps on bonuses.

The union has threatened to stage an 18-day walkout starting May 21 if negotiations with management fail and claims that such action would cost the company more than 1 trillion won ($676 million) a day.

“We won’t stop this fight until our fair demands are met,” Choi Seung-ho, a union leader, said through a loudspeaker from atop a crane-mounted structure.

While semiconductor makers have benefited from the AI boom, the war in the Middle East has clouded the future outlook, disrupting supplies of key materials such as helium that are crucial to chipmaking and pushing up energy costs.

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Kim Tong-hyung reported from Seoul, South Korea. AP writer Hyung-jin Kim contributed to the report from Seoul.

Yong-ho Kim And Kim Tong-hyung, The Associated Press