The de facto chief of South Korea's Samsung business empire faces the verdict Monday in his retrial over a sprawling corruption scandal, a ruling that could see him jailed for years, depriving the tech giant of its top decision-maker.

Officially, Lee Jae-yong is vice-chairman of Samsung Electronics, the world's biggest smartphone and memory chip maker, but he has effectively been at the head of the massive Samsung group for several years after his father was left bedridden by a heart attack, finally dying in October.

Samsung is by far the biggest of the family-controlled conglomerates, or chaebols, that dominate business in the world's 12th-largest economy.

Its overall turnover is equivalent to a fifth of the national gross domestic product and it is crucial to South Korea's economic health.

Lee was jailed for five years in 2017 for bribery, embezzlement and other offences in connection with the scandal that brought down South Korean president Park Geun-hye.

An appeals court dismissed most of his bribery convictions and gave him a suspended sentence the following year, but the Supreme Court later ordered the 52-year-old to face a retrial.

The case centres on millions of dollars the Samsung group paid Park's secret confidante Choi Soon-sil, allegedly for government favours including ensuring a smooth transition for Lee to succeed his then-ailing father.

The scandal highlighted shady connections between big business and politics in South Korea, with the ousted president and her friend accused of taking bribes from corporate bigwigs in exchange for preferential treatment.

In May, Lee made a rare public apology, bowing before flashing cameras for company misconduct including the firm's controversial plan for him to ascend to the leadership.

His own children, he promised, would not succeed him in top management roles at the company.

Both Lee's father Lee Kun-hee and grandfather -- Samsung founder Lee Byung-chull -- had brushes with the law themselves but never served time behind bars.

Earlier this month, Samsung Electronics, the group's flagship subsidiary, flagged a jump of more than 25 percent in fourth quarter operating profits, citing benefits from pandemic-induced working from home that boosted demand for devices powered by its chips.

Analysts forecast a stable outlook for the company in 2021, driven by continued demand for memory chips.

Its rise has been driven by a willingness to invest billions in strategic bets on key technologies, but experts say Monday's ruling could hamper its decision-making on future large-scale investments if Lee is jailed. AFP