The younger son of the Lotte Group's founding family has strengthened his hold on the South Korean conglomerate amid a bitter succession feud with his elder brother, winning the backing of shareholders at a key Tokyo-based holding company.

An extraordinary shareholders' meeting at unlisted Lotte Holdings approved a proposal calling for the company led by co-CEO Shin Dong-bin, the younger son of 92-year-old founder Shin Kyuk-ho, to establish a stable management structure and strengthen its corporate governance.

The vote had been closely watched to see if Dong-bin, who is also the chairman of Seoul-based Lotte Group, would muster sufficient support after his elder brother Shin Dong-joo said he and his father were opposed to Dong-bin gaining sole control of the conglomerate.

The conglomerate, with operations that span retail, confectionery, hotels and chemicals, had until last year been divided between the two brothers with the younger running the much bigger South Korean operations and the elder running the Japan businesses.

The elder son appeared to fall out of favour early this year but later seemed to have regained his father's support. Family infighting escalated in July after the father and elder son flew to Tokyo to dismiss the board at Lotte Holdings - an attempted coup that failed after the younger son sacked his father as co-CEO of the Japan-based firm.

Lotte Group has since said that the founder has "difficulties making judgments". Thirty-seven CEOs at Lotte's South Korean units have also publicly voiced their support for Dong-bin.

Lotte Holdings did not immediately offer a breakdown of how close the shareholder vote was. A spokesman said the elder brother Dong-joo attended the meeting but the father did not. He declined to comment on whether Dong-joo had made statements at the meeting, which lasted about half an hour.

About one-third of Lotte Holdings is held by employees, another third owned by subsidiaries or associations and the remaining third is held by an investment company that the Shin family controls, Dong-bin said last week, adding that he himself held only 1.4 percent.

Dong-bin announced last week an up-to-$6 billion revamp of Lotte Group, which includes listing key Korean business Hotel Lotte Co Ltd as soon as possible.