The world's biggest smartphone and chipmaker Samsung Electronics issued a rare apology Wednesday after its chairman was jailed for sabotaging union activities.

Chairman Lee Sang-hoon and executive vice president Kang Kyung-hoon were both jailed for 18 months for leading a wide-ranging operation to deter staff at Samsung's customer service unit operating a union.

Samsung Electronics is the flagship subsidiary of the Samsung group, by far the biggest of the family-controlled conglomerates known as chaebols that have propelled South Korea's rise to the world's 11th-largest economy.

Along the way it has fought ferociously against union representation, until local authorities in Suwon, where it is headquartered, last month certified the National Samsung Electronics Union, which is affiliated to a powerful umbrella group.

Lee and Kang were found guilty Tuesday of violating labour union laws, with prosecutors saying they had ordered subordinates to cut union members' wages and discover and exploit details of their personal lives such as pregnancies and debt, among other tactics.

At the time Lee was Samsung Electronics' chief financial officer, and both men have been members of the now-disbanded Future Strategy Office, its key decision-making body.

The chairman and executive vice president of Samsung Electronics were both jailed for 18 months for sabotaging union activities
The chairman and executive vice president of Samsung Electronics were both jailed for 18 months for sabotaging union activities AFP / Jung Yeon-je

The firm issued a joint statement Wednesday with construction affiliate Samsung C&T -- which has also had executives convicted of violating union laws -- acknowledging their errors.

"We humbly accept that the companies' understanding and view towards labour unions in the past fell short of society's expectations," they said.

They pledged to ensure no repetition, adding: "We will endeavour to build a forward-looking and productive labour management relationship based on the respect for our employees."

Samsung's founder Lee Byung-chul, who died in 1987, was adamantly opposed to unions, saying he would never allow them "until I have dirt over my eyes".

Labour campaigners say that over the years about 240 people have suffered from work-related cancers and other illnesses after being employed at Samsung semiconductor and display factories, with around 80 of them dying -- many of them young women.

One victim's father, Hwang Sang-ki, has said: "My daughter died because Samsung had no unions".

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