SEOUL (Reuters) - South Korea’s Supreme Court is to rule next Thursday on whether to uphold a reduced sentence given to Samsung Group heir Jay Y. Lee or ask an appeals court to revisit a case that was part of a graft scandal that brought down the president in 2017.

FILE PHOTO - Samsung Electronics Vice Chairman, Jay Y. Lee, arrives at a court in Seoul, South Korea, October 12, 2017. REUTERS/Kim Hong-Ji

The ruling will be a test of South Korea’s pledge to reform dominant conglomerates criticised for cozy relationship with political leaders, at a time when the Asia’s fourth-biggest economy is facing a series of headwinds.

The 51-year old Lee was convicted of bribing Choi Soon-sil, a close friend of former President Park Geun-hye.

Prosecutors have alleged that he paid bribes to help secure control of Samsung Group, South Korea's top conglomerate that owns Samsung Electronics 005930.KS, the world’s leading smartphone and chip maker. He denied the charges.

He received a five-year jail term in 2017, but was released in 2018 after an appeals court reduced his punishment to a suspended prison sentence on charges of bribery, embezzlement and other convictions.

Both Lee and state prosecutors appealed to the Supreme Court, leaving the top court with the options of either upholding the appeals court’s ruling or asking it to reconsider its judgment, legal experts say.

Samsung declined to comment.

The Supreme Court is also set to rule on appeals court decisions in the cases against Park and Choi.

Park, who was impeached following the scandal, received a jail sentence of 25 years, while Choi was jailed for 20 years. They were both fined of 20 billion won ($16.53 million).

Park Sang-in, an economics professor at Seoul National University, said a trade rift between South Korea and Japan could put pressure on the court to be lenient with Lee, considering Samsung’s role in the economy, but that could undermine South Korea’s image in financial markets.

Japan last month tightened controls on exports to South Korea of high-tech materials used to make chips - the bread-and-butter business of Samsung Electronics.

Samsung's biotech affiliate, Samsung BioLogics 207940.KS, is also under investigation from prosecutors over a suspected accounting fraud, with some executives arrested for their alleged roles in the case.