CAMP FOSTER (Japan) - THE US Marines are considering expanding weekend patrols on the southern Japanese island of Okinawa amid outrage after alleged crimes by US soldiers, a senior officer said on Tuesday.

The US military and the Japanese government started studying launching joint patrols in Okinawa, home to more than half the US troops in Japan, after a US Marine allegedly raped a 14-year-old girl last month.

Lieutenant Colonel Douglas Powell, director of public affairs for the US Marine Corps in Japan, said the military has already been conducting patrols on its own to curb misconduct.

'We are looking at expanding it to a few more areas,' he said.

Following last month' alleged rape, the US military imposed a round-the-clock curfew for about two weeks on its soldiers and their relatives in Okinawa and at two other US bases in Japan. US soldiers are still under a curfew from 10 pm to 5 am and restricted from drinking alcohol off bases except at private homes linked to the military.

But 6,000 residents demonstrated under pouring rain on Sunday, calling for further measures to stop crime by US troops.

'One incident is too many here because we are guests in Japan,' Mr Powell said.

But he also said he cannot guarantee no further crimes will be committed.

'I cannot promise you. We have 50,000 US service members,' including civilian base personnel and relatives in Okinawa, the officer said.

'We've put forth our best efforts to prevent misconduct and incidents and accidents,' he added.

'We have been successful on that.'

'The bottom line is that Japanese people want us here. We are here because of the mutual defence cooperation treaty,' he said.

More than 40,000 US troops are stationed in Japan under a security treaty to defend Washington's key Asian ally, which has been officially pacifist since World War II. -- AFP