The sides could not bridge gaps at two days of talks in Washington on the conditions under which a US representative could be present during police interrogation of US military personnel charged with a crime in Japan.

In a written response to a question taken at his daily press briefing on Friday, State Department spokesman Richard Boucher said large gaps still remained between the two sides.

"Although both sides expended considerable effort to refine and explain their respective proposals, substantial differences continue to exist," he said.

"Both sides acknowledged that the four meetings had been useful in deepening each other's understanding of their respective positions."

"The two sides continue to study each other's proposals and will report the outcome of the series of meetings to their respective senior officials for the consideration of future steps," he said.

In Japan, an unidentified official was quoted as telling Kyodo news: "The two countries need to continue to work with each other, showing more flexibility."

The Japan-US Status of Forces Agreement governs the presence of the US military in Japan and its 47,000 troops.

The document has come under attack from Japanese politicians after a number of US soldiers have been charged and convicted in high-profile rape cases.

In July, Japanese prosecutors indicted 21-year-old US Marine Lance Corporal Jose Torres for allegedly beating and raping a woman on the southern Japanese island of Okinawa in May.

Torres admitted to the allegations, prosecutors said.

The Japan-US accord does not require the transfer of military personnel to local authorities before an indictment, but US authorities have handed over suspects in certain cases.

The accord was sparked by the gang rape of a 12-year-old Okinawan girl by three US servicemen in 1995, which led to massive protests.

WAR.WIRE