TOKYO (AFP) - The US Navy said on Friday (June 10) it lifted restrictions preventing sailors in Japan from leaving their bases four days after the rule was imposed following a drunk-driving case on Okinawa.

However, an alcohol ban for sailors in the country, also imposed on Monday, will be maintained, it said in a release.

The United States has come under intense pressure to rein in bad behaviour by its military and related personnel after a series of recent crimes on Okinawa, including the suspected rape and murder of a 20-year-old local woman.

Such crimes have long sparked protests on the strategic southern island crowded with American bases and have been an irritant in relations between Tokyo and Washington - key Asia-Pacific security allies.

US President Barack Obama last month during a visit to Japan vowed measures to prevent crimes by Americans and the military imposed restrictions including a curfew after a civilian base employee was arrested on Okinawa in connection with the alleged rape and murder.

As a further measure, the US Navy announced on Monday alcohol bans and base restrictions for its sailors in Japan after one was arrested on Okinawa at the weekend for allegedly driving while intoxicated and injuring two people, one seriously.

But in a statement Friday, the navy said it lifted the base restrictions after confirming that "all sailors had received face-to-face training" from superior officers and others.

But sailors must now "submit to their chain of command a detailed liberty plan which accounts for all off-duty hours spent off base", it added.

The statement also said that the drinking ban will stay in place until top officers "are comfortable that commands have conducted training, which deglamorizes the use of alcohol, and that all personnel fully understand their responsibilities as ambassadors of the United States".

Okinawans are planning a major rally later this month in protest over the bases, as well as the behaviour of US personnel.

More than half the 47,000 American troops in Japan under a decades-long security alliance are stationed on Okinawa, the site of a major World War II battle that was followed by a 27-year US occupation of the island.