In return for the bribes, prosecutors allege, Lee won the government's blessing for a merger between two Samsung subsidiaries under terms designed to increase his control over the entire Samsung empire so as to cement a power transfer from his ailing father Lee Kun-hee.

Lee, 49, was also accused of other charges, such as embezzlement, hiding assets overseas, concealment of criminal proceeds and perjury, all stemming from the corruption scandal that rocked South Korea for months, sparking massive street protests and ultimately forcing Park out of office.

Lee, who has been under pre-sentencing detention since February, denies the charges.

His lawyers have claimed that Lee was neither involved in nor knew of Samsung's decision to offer the money and other top executives, including Choi Gee-sung who headed the now-defunct Future Strategy Office that oversaw key decisions, made the call for fear of retaliation from Park and Choi.

Lee also claimed that he never sought any government favors when he met with Park one-on-one three times.

A guilty verdict is expected to deal a blow to the image of Samsung, South Korea's biggest conglomerate with dozens of subsidiaries that accounts for about a quarter of the country's gross domestic product and total exports.

A prison term for Lee could also raise questions about what long-term effects the prolonged leadership vacuum would have on the world's largest smartphone maker, even though its short-term performance appears unaffected, with its second-quarter profit reaching a record high due in part to strong sales of its newest Galaxy S8 smartphone.

Friday's verdict is closely linked to ousted former President Park because Lee's conviction of bribery charges would mean that Park could also been found guilty. She was arrested in late March on a string of charges, including bribe-taking.

The case has also been seen as a litmus test of tolerance South Korean courts have toward owners of family-run chaebol. In many corruption cases in the past, courts often sentenced tycoons to suspended or light terms, citing their contribution to the country's economy. (Yonhap)