The case centred on whether three horses donated by Samsung Group for the training of the competitive equestrian daughter of Park's friend should be considered bribes aimed at winning the president's favour.

The Supreme Court said the appeals court erred in not recognising the horses as bribes given by Samsung to win favours.

The ruling cast doubt whether Lee, 51, can focus on steering the group's flagship Samsung Electronics Co Ltd through falling profitability and Japanese export curbs on materials crucial for the world's leading chipmaker.

Lee, vice chairman of Samsung Electronics, was sentenced in 2017 to five years imprisonment for bribing a friend of Park as he sought to succeed his father and secure control of Samsung Group.

He was freed after a year in detention when the appellate Seoul High Court halved his sentence and suspended it for four years. Both Lee, who denies wrongdoing, and prosecutors appealed.

Samsung Electronics shares extended losses to a decline of 2 percent after the ruling, while those of affiliates Samsung Bio Logics Co Ltd and Samsung C&T Corp fell nearly 8 percent and 6 percent. (Reuters)