The chairman of South Korea's sprawling SK Group was ordered by a court on Thursday to pay his wife US$1 billion in cash in the country's largest divorce settlement.

The Seoul High Court ordered Chey Tae-won to pay Roh So-young, the daughter of former president Roh Tae-woo, 1.38 trillion won as a settlement, court documents showed.

The amount was a significant increase from an earlier lower court ruling of 66.5 billion won and takes into account the contributions Roh So-young and her father made to Chey's success.

SK Group runs businesses that include South Korea's leading mobile carrier and also controls SK Hynix, the world's second-largest memory chip maker.

"It was reasonable to rule that, as his wife, Roh played a role in increasing the value of SK Group and Chey's business activity," the court said.

Chey married Roh So-young in 1988 but they have been separated for years. She appealed against the original settlement amount awarded in 2022, several years after Chey filed for divorce in what has become an acrimonious case.

The court said the new settlement also took into account the emotional suffering Roh So-young endured due to Chey's extramarital affair.

Chey has a child with his new partner.

The court said Chey "is not showing any signs of remorse for his foul behaviour in the course of the trial... nor respect for monogamy," ordering him to pay the settlement in cash.

Chey's net wealth was assessed by the court to be around four trillion won, meaning Roh So-young will take 35 percent of it in the settlement.

His legal team said they would lodge an appeal against the latest ruling, claiming the court had "taken Roh's one-sided claim as factual."

The Seoul High Court said Roh Tae-woo also helped Chey's business flourish during his five years as president from 1988, easing regulatory hurdles for SK's late former chairman Chey Jong-hyon, Chey Tae-won's father.

"Former president Roh Tae-woo played the role of a protective shield for ex-chairman Chey Jong-hyon" when the late businessman was trying to tap into the mobile carrier business, the court said, giving "intangible help" to the family.

Chey's lawyers disagreed, saying SK Group had been under pressure from the Roh government and had "provided various financial contributions."

"We will set things straight through the appeal," they said.

A former general, Roh Tae-woo was elected to the presidency in 1987 polls that were South Korea's first free and fair election in more than a decade.

He had earlier helped his military academy friend Chun Doo-hwan stage a military coup and take over as a dictator. (AFP)