Blackstone last month offered to buy the company at 5,000 yen a share, which valued the hotel chain at 171 billion yen (£1.2 billion). It also warned the company that it would take any measures if Unizo fails to respond to Blackstone's offer by a deadline that it keeps extending. Its initial deadline was Oct. 23.

"Unfortunately, despite our sustained good faith efforts, as of the date of this release, Blackstone has been unable to reach a definitive agreement with Unizo," Blackstone said in a statement.

Unizo was a little-known property manager until Japanese travel agent H.I.S. Co Ltd launched a hostile bid for it in July.

Unizo had at one stage turned to U.S. buyout firm Fortress Investment Group, which is owned by SoftBank Group Corp, to fend off the bid from H.I.S., but later withdrew its support for Fortress' white-knight offer.

Fortress is running its public tender offer at 4,100 yen per share.

Blackstone said it would provide an update no later than Dec. 6 if there are any changes in circumstances regarding Unizo.

Unizo shares closed at 4,975 yen on Wednesday.

(Reporting by Junko Fujita; Editing by Lisa Shumaker)