The vice chairman of South Korea's Lotte Group has been found dead hours before he was to be questioned in a corruption probe.

The firm confirmed the death of Lee In-won but did not give a cause of death.

The 69-year-old was to be questioned on Friday in an investigation into a possible slush fund and financial irregularities in the company.

According to local media, investigators found a suicide note in his car.

Mr Lee was one of the most senior executives in the Lotte Group, holding the highest position outside the founding family that still runs the firm.

He was also the closest aide to chairman Shin Dong-bin who is embroiled in afamily feud with his older brother over control of the company founded by their father.