A South Korean court has sentenced billionaire Samsung heir Jay Y Lee to five years in prison after finding him guilty of offering bribes to the country's former president and other crimes.

Key points: The court said Lee bribed Park Geun-hye to win support for a controversial merger

The court said Lee bribed Park Geun-hye to win support for a controversial merger He showed no particular reaction after his sentence was announced

He showed no particular reaction after his sentence was announced South Korea has a history of pardoning tycoons convicted of similar offences

It said Lee, 49, was also guilty of embezzlement, hiding assets overseas, concealing profit from criminal acts and perjury.

The court said Lee hoped bribes for Park Geun-hye at the time she was president and her close friend Choi Soon-sil would secure government support for a merger that strengthened Lee's control over the Samsung empire and its flagship Samsung Electronics at a crucial time.

"This case is a matter of [Lee] and Samsung Group executives, who had been steadily preparing for Lee's succession … bribing the president," Seoul Central District Court Judge Kim Jin-dong said.

Mr Kim said that as the group's heir apparent, Lee "stood to benefit the most" from any political favours for Samsung.

Lee showed no particular reaction after his sentence was announced, and took a small sip of water as he stood up to leave the courtroom.

A lawyer for Samsung heir Lee Jae-yong said the billionaire's legal team will appeal a five-year prison sentence for bribery and other crimes.

"As a lawyer I cannot possibly agree with the juridical decisions and acknowledged facts involved in the verdict," Samsung attorney Song Woo-cheo said outside the court.

"We will appeal against the decision and I am sure that in the appellate trial all the charges will be dismissed."

The Samsung heir denied wrongdoing and has been in detention since February. ( Reuters: Jung Yeon-je )

A maximum of two appeals are possible in the case.

Lee's attempts to bribe former president Park contributed to her ouster and arrest earlier this year.

The Samsung heir denied wrongdoing and has been in detention since February.

Samsung facing leadership vacuum

There was no immediate official statement from Samsung following the verdict.

The third-generation de facto head of the powerful Samsung Group, Lee has effectively directed operations since his father Lee Kun-hee was incapacitated by a heart attack in 2014.

Many tycoons, including Lee's father, were convicted of crimes in the past, ranging from bribery, embezzlement and tax evasion, only to get presidential pardons as both the government and the public feared going too hard on them would hurt the economy.

Moon Jae-in has promised to end the practice of pardoning white collar criminals. ( AP: Ahn Young-joon )

But South Korea's new liberal president, Moon Jae-in, who won a May election, has pledged to rein in the chaebols, empower minority shareholders and end the practice of pardoning tycoons convicted of white-collar crime.

There was no immediate comment from the government, but Mr Moon told Reuters in an interview in June he did not believe Samsung's operations depended just on Lee.

Some investors worry a prolonged leadership vacuum, with no one to make big decisions, could slow decision-making at the group, which has more than five dozen affiliate companies and assets of 363.2 trillion won ($407 billion).

Its listed companies make up about 30 percent of the market value of South Korea's KOSPI stock index.

Shares of Samsung Electronics dropped more than 1 percent and other group companies, including Samsung C&T and Samsung SDS , also turned lower after the verdict.

Reuters/AP