The U.S. Embassy in Japan has advised Americans to avoid bars and clubs in central Tokyo's Roppongi nightlife area, saying on its website that there had been a sharp rise in cases of Americans being served spiked drinks.

The U.S. Embassy in Japan has advised Americans to avoid bars and clubs in central Tokyo´s Roppongi nightlife area

"Typically, the victim unknowingly drinks a beverage that has been secretly mixed with a drug that renders the victim unconscious for several hours, during which time large sums of money are charged to the victim's credit card or the card is stolen outright," the Embassy said.

A Tokyo Police spokesman said no claims had been filed about such incidents in recent weeks. The U.S. Embassy was unable to confirm how many cases it had been advised of.

Among the entertainment on offer in Roppongi are hostess bars, where men pay hundreds of dollars to drink and chat with women.

"The crime in Roppongi is kind of a recurring problem, unfortunately," said U.S. Embassy spokeswoman Lori Shoemaker.

Roppongi has been home to large numbers of restaurants and bars since the suburb was home to a U.S. Army base after World War Two.

Briton Lucie Blackman was killed while employed by a Roppongi hostess bar in 2000. Her remains were later found in a seaside cave.

News item courtesy of www.reuters.com