Local media said a credit card belonging to a sailor was discovered in the taxi where Masaaki Takahashi, 61, was found with stab wounds in his neck.

The US Navy said it was helping police in Yokosuka, near Tokyo, to find the sailor following Wednesday's murder.

There are about 50,000 US personnel in Japan, and the relationship with the local population is often uneasy.

A number of criminal allegations have been made against servicemen in recent years.

Most recently, a US marine was accused of raping a 14-year-old girl. The case triggered protests on the island of Okinawa but was later dropped.

Police have not named the sailor they are hunting and refused to say whether he is a suspect in the murder.

Cmdr David Waterman, a US Navy spokesman, told the Associated Press the sailor "may have information pertinent to the case".

"Since the incident happened close to the base, both US Navy and Japanese authorities are interested in talking to a number of persons, including a US sailor," he said.

Japanese media reported that the serviceman had been missing from the Yokosuka base for several weeks.