SEOUL (Reuters) - Samsung Electronics' ( SSNLF ) union in South Korea has declared it will start taking strike action, including advising members as an initial protest to take annual leave on June 7, a union official said during a live-streamed press conference on Wednesday.

The union accounts for about 28,000 workers, or more than a fifth of the company's total workforce, according to union officials.

A group of union officials made the announcement while holding a banner which read: "We can no longer tolerate labour repression, union repression."

Samsung Electronics ( SSNLF ) did not have an immediate comment.

More than 2,000 unionised workers of the South Korean technology giant gathered in Seoul last week to hold a rare rally to demand better wages.