Lotte Group has officially rejected the request of former vice chairman of Lotte Holdings Shin Dong-joo to begin sending him business reports on its core affiliates, dismissing the move as “lacking legal grounds.”

The elder son of the group founder is engaged in a bitter feud with his younger brother, Lotte Group chairman Dong-bin, over control of the group since he was ousted from key posts at its Japanese units in January. 

Dong-joo stepped up his counterattack against his younger brother last Tuesday, expelling Dong-bin from the board of Kojyunsya, the virtual holding company of Lotte Holdings with a majority stake of 28.1 percent.

Following the move, Dong-joo also clashed with his brother last Friday over the control of their father and Lotte founder and general chairman Shin Kyuk-ho’s main office, located on the 34th floor of Lotte Hotel Seoul, deploying seven of his employees at SDJ Corporation. Dong-joo created the company to push for legal action against his brother.

Two days later, he demanded Lotte Group to send him the business reports usually received by the Lotte general chairman, claiming authority over the group’s operations.

Lotte Group refused the demand Sunday, saying in a statement that Dong-joo may be “stepping outside his legal authority” by asking the group to share such information.

“SDJ is a company entirely unrelated to Lotte. Sharing inside information related to Lotte’s core affiliates can amount to data leakage, which can have legal repercussions,” the group said.

Dong-joo, who showed up at his father’s office Monday, reportedly plans to continue going there every day, as he is able to access the office freely.

The elder Lotte son has also asked his younger brother to remove the group’s employees and surveillance cameras installed inside the office, according to SDJ Corp.

The dispute is the latest development in one of the nation’s biggest-ever family power struggles over ownership of the 90 trillion won ($80 billion) South Korean retail giant which is governed by a complex, circular shareholding structure.

In January, Dong-joo was ousted from his post as vice chairman of Lotte Holdings, in a move hinting that the younger son Dong-bin would become the next leader of the Lotte empire in Korea and Japan.

The feud was sparked on July 27, when chairman Shin Kyuk-ho, 92, suddenly dismissed Dong-bin from the board, in a move led by Dong-joo. The next day, Dong-bin and the board of Lotte Holdings voted to remove his father from his post, relegating him to the position of honorary chairman.

By Sohn Ji-young (jys@heraldcorp.com)