The mystery businessman who put up a reward for information about missing British hostess Lucie Blackman has upped the ante -- increasing the reward to a cool half a million pounds, more than 77 million yen.

The British entrepreneur, who refuses to reveal his identity, contacted The Japan Times to announce that he is increasing the fund "in an effort to track down Lucie and reunite her with her family."

Lucie, a 22-year-old former British Airways flight attendant from Sevenoaks in Kent, was working as a hostess at the Casablanca club in Tokyo's Roppongi entertainment district before she disappeared on July 1. She has not been seen since.