Prime Minister Yoshiro Mori on Wednesday shrugged off suggestions that he had wagered on the round of golf he continued after learning of the sinking of the Ehime Maru, which had been struck by a U.S. submarine.

"It is hardly possible that I would play golf for stakes," the prime minister told reporters at his official residence.

The Mainichi Shimbun reported Wednesday that Mori is believed to have been betting money on the outcome of the golf game at a country club in Yokohama.

The daily quoted Mori's office as saying that Mori could have been betting "what is the equivalent of a bar of chocolate."

Chief Cabinet Secretary Yasuo Fukuda said he was not aware of what transpired at the golf course on the day but that it is common to play golf for bars of chocolate.

"The intention is to make the golf game more interesting," the top government spokesman said at a news conference, adding that "chocolate" is not slang for cash, as suggested by the newspaper.

"It is not as if we are thinking about winning a large number of them and making a business out of it," he said.

Mori is under fire for continuing to golf for about two hours after being informed about the tragedy, in which nine of the 35 people aboard the fisheries training ship, including four 17-year-old high school students, are missing and presumed dead.