TOKYO -- Japanese police on Thursday obtained an arrest warrant for a US sailor suspected of stabbing a taxi driver to death last month, a Japanese official said.

Police aim to arrest the 22-year-old serviceman later in the day after the Japanese government formally demands his handover, a foreign ministry official told Agence France-Presse.

"We will soon make the demand to the US side," the ministry official said on customary condition of anonymity.

According to local media, the sailor has admitted to police to killing 61-year-old Masaaki Takahashi, who was found dead with a kitchen knife in his neck near the Yokosuka naval base at the mouth of Tokyo Bay.

The US military on Wednesday announced a night-time curfew for personnel at Yokosuka, its biggest naval base in Japan, limiting movements between the hours of 10 p.m. and 6 a.m. to journeys to work and essential errands.

The sailor's credit card was reportedly found in the parked taxi where the driver was discovered murdered on March 19. Reports said the taxi driver may have argued with his customer over the fare.

The sailor, a Nigerian national, will be transferred to Japanese custody as early as Thursday "once the US side agrees to his handover," the ministry official said.

Japan needs the agreement of the United States to take custody of a US serviceman before obtaining an indictment.

"I believe the United States will swiftly respond to the demand by the Japanese government," top government spokesman Nobutaka Machimura told reporters earlier.

The United States on Thursday renewed its pledge to cooperate with Japan over the investigation.

"His brutal murder is a shock and an outrage to all those who believe in a civilized society," US Ambassador to Japan Thomas Schieffer said in a statement.

The killing is the latest in a series of high-profile alleged crimes in Japan linked to US servicemen that have strained relations between the US military and local communities.

Among other past cases, a 22-year-old US sailor from the aircraft carrier USS Kitty Hawk was sentenced to life in prison by a Japanese court for kicking and beating a 56-year-old woman to death in 2006 in Yokosuka.

More than 40,000 American troops are stationed in Japan, which became officially pacifist after World War II.

The US military also imposed a curfew on troops in southern Okinawa in February following an alleged rape of a 14-year-old girl. The military eased those restrictions after nearly two weeks but still has a nighttime curfew.