A workers' union at Samsung Electronics in South Korea said on Monday it would launch a general strike until its demands for better pay and time off were met, warning of more damaging action against the country's most powerful conglomerate than its one-day walkout last month.

The National Samsung Electronics Union, whose roughly 28,000 members make up over a fifth of the firm's workforce, is planning to begin the strike on July 8, asking the company for commitments such as improvements to its performance-based bonus system and an extra day of annual leave.

"We are declaring a general strike today," Son Woo-mok, president of NSEU, said on a live YouTube broadcast. "Until our demands are met, we will fight with the 'no pay no work' general strike."

The union will provide more details regarding the strike on Tuesday, it said in a statement.

Samsung Electronics did not provide an immediate comment.

Last month, the union staged a walkout by using an annual leave, its first such industrial action, but the company at the time said there was no impact on production or business activity.

As the world's top memory chipmaker and a major global smartphone maker, Samsung Electronics' run of success is being challenged in some areas, including in some cutting-edge chips.

It recently replaced the head of its semiconductor unit to navigate what it called a "crisis" affecting the industry.

Any larger scale or protracted industrial action would be a headache for Samsung as it scrambles to catch up with rivals making high bandwidth memory (HBM) chips used in AI applications.

Union membership increased rapidly after Samsung in 2020 pledged to end to its practice of discouraging the growth of organised labour. (Reuters)