By Ju-min Park

SEOUL (Reuters) - Against a backdrop of K-pop performances and dance music, more than 2,000 unionised workers from Samsung Electronics ( SSNLF ) gathered in Seoul on Friday, holding a rare rally to demand the South Korean technology giant pay fair wages.

Over the last two years, the National Samsung Electronics Union (NSEU) has seen its membership swell four-fold to about 28,000, or more than a fifth of the company's total workforce, union officials said.

The rapid growth of the union's membership comes after the country's most powerful conglomerate pledged in 2020 to put an end to its practices of discouraging the growth of organised labour.

Jay Y. Lee, chairman of Samsung Electronics ( SSNLF ), had at the time publicly apologised for scandals over union-busting tactics and declared an end to a "no-union" philosophy.

Government data shows employee union membership levels have not risen in South Korea for the past two decades and remain relatively low compared to some other OECD countries. But more young workers are becoming convinced about the benefits of unionisation, union officials have said.

Chanting "respect labour", the unionised engineers and office workers were also entertained by electronic dance music played by a well-known comedian-turned-DJ, who dresses as a Buddhist monk.

K-pop singers also performed, prompting unionised workers in their 20s and 30s to clap and dance, with the rally near Samsung's office in the glitzy Gangnam district of Seoul at times resembling a street party.

"Our rallies are non-violent but we can still show our strength," said Choi Young-wook, a 27-year-old Samsung chip engineer, who wore a black cap with the union's logo.

LEAVES, BONUSES

The rally comes as Samsung's run of success appears to be faltering in some areas, including cutting-edge semiconductor chips.

Samsung this week replaced the head of its semiconductor unit saying a new person at the top was needed to navigate what it called a "crisis" affecting the chips industry.

The company has decided to increase wages this year by 5.1% and while the union does not necessarily oppose such a hike it wants one more day in annual leaves as well as transparent performance-based bonuses, the union has said.

Negotiations between the company and the union resumed on May 21, according to the union, though some officials questioned the company's commitment to consulting with them.

In a statement to Reuters, Samsung Electronics ( SSNLF ) said that working-level negotiations had resumed, and the main negotiations were scheduled to take place on May 28.

"We will sincerely engage in discussions with the union," said the statement.

Union officials say that among younger employees there is a growing perception that unions can help create a fairer workplace, whereas the older generation in the company felt unions could disrupt work productivity.

Overall, South Korea's union membership rate has hovered around the 10% level since 2004, according to data from the labour ministry.

"More and more people inside the company are realising why they need unions, which is to have a voice, and we are getting empowered by these people day by day," said Son Woo-mok, president of NSEU, who began working at Samsung in 2005.

(Reporting by Ju-min Park; Editing by Ed Davies and Muralikumar Anantharaman)