SHOWA SHELL SEKIYU KK 
TOKYO (Reuters) - Idemitsu Kosan's (>> Idemitsu Kosan Co., Ltd.) founding family, locked in a battle with the firm's management over a proposed buyout of a rival, said on Monday it had increased its stake in the Japanese refiner by nearly 2 percentage points to more than 28 percent.
The family bought more shares in Idemitsu after having its holding diluted when the company sold new stock earlier this year, Yohei Tsuruma, the family's lawyer, said in a statement.
The descendants of founder Sazo Idemitsu remain opposed to a takeover of Showa Shell Sekiyu (>> Showa Shell Sekiyu KK), Tsuruma said.
Idemitsu said in August that the earlier share sale had diluted the founding family's stake in the company to about 26 percent, from more than a third previously, eliminating the family's veto power over a buyout of Showa Shell.
The family has increased its stake to 28.0003 percent for about 15.576 billion yen (£103 million), a spokeswoman for the founding family said.
It held 26.093 percent in the refiner immediately after the new share sale in July, she said.
In response to the family's announcement, an Idemitsu spokesman said there is no change in the company's stance to seek talks with the family about the buyout plans.
In a rare public corporate battle, the founding family and the board have been disputing the Idemitsu-Showa Shell merger for about two years, through court and shareholder actions.
The family, led by Shosuke Idemitsu, has said the two companies are too different for any merger to work, while the board says the combination is necessary to compete in Japan's shrinking oil products market.
(Reporting by Osamu Tsukimori; Writing by Aaron Sheldrick; Editing by Himani Sarkar and Tom Hogue)
