Bain says to extend $1.35 bln bid deadline for Japan's Asatsu-DK

TOKYO, Nov 2 (Reuters) - U.S. private equity fund Bain Capital plans to extend a deadline for its $1.35 billion bid for Asatsu-DK Inc by around a week to give shareholders more time to review the deal after Asatsu-DK shareholder WPP took legal action, a senior Bain official said on Thursday.

WPP, the world's largest advertising group, said it was taking legal action against its partner Asatsu-DK, deepening an acrimonious spat over the Japanese advertising agency's backing for the takeover deal.

Last month, Asatsu-DK said it had told WPP that it planned to end their two-decade business alliance, and asked WPP to sell its shares to Bain.

In response, WPP said on Thursday in an emailed statement that it was seeking arbitration with a Japanese arbitration body and a preliminary injunction with the Tokyo District Court, claiming it is entitled to retain its shareholding in Asatsu-DK.

David Gross-Loh, head of Bain's Asia business, told Reuters it plans to extend the Nov. 15 tender offer deadline to Nov. 21 to comply with local financial regulations, but the fund believes its offer of 3,660 yen per share is full and final.

"We are not interested in raising the price," said Gross-Loh.

Japanese financial regulations requires a tender offer deadline to be adjusted when new information that could impact shareholders' decisions is released, Gross-Loh said. (Reporting by Junko Fujita; Editing by Miyoung Kim and Ian Geoghegan)