The yard's union said members walked out after completing their eight-hour shift, refusing to carry out a scheduled extra hour of work, AFP reported.

"After today's walkout, we will step up our action and may launch a strike involving all our members if the company continues to reject our demands," union leader Park Kyung-Soo said.

A four-hour stoppage will follow on 27 November unless pay demands are met, the Maeil Daily said.

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