The United States is ready to move 4,700 Marines from the Japanese island of Okinawa to Guam even without progress on plans to relocate a US base in Japan, officials said Tuesday.

The decision is expected to be announced by Tokyo and Washington within days following talks on Monday in Washington between senior representatives from each government, two US officials told AFP.

In 2006, the United States and Japan agreed to the transfer of around 8,000 Marines from Okinawa to the American territory of Guam and the relocation of the Marine Corps Air Station Futenma on Okinawa.

The transfer of the American forces had always been linked to relocating the Marine air base, but the plan has been bogged down as Tokyo has faced strong opposition from Okinawans over the deal.

In a policy shift, Washington is now prepared to pull out more than half the troops to Guam while awaiting progress on the base relocation, officials said.

"What we're looking to do is de-link the movement of forces to Guam and the Futenma replacement facility," one defense official said.

By scaling back the US military footprint, "it will reduce some of the stress" on Okinawa, said the official, who spoke on condition of anonymity.

The earlier transfer to Guam was first reported in Japanese media. But US defense officials and military officers could not confirm reports in Japan saying the remaining 3,300 Marines in Japan would be redeployed to other countries in Asia.

A Pentagon spokeswoman, Commander Leslie Hullryde, declined to confirm if an announcement on a troop transfer was imminent but said the United States and Japan are "continuously looking for more efficient and effective ways to achieve the goals of the Realignment Road Map."

She said the US government "remains committed to enhancing the US-Japan Alliance and strengthening operational capabilities while significantly reducing the impact of US bases on the Okinawan people."

Many Okinawans, angry at having for decades shouldered the burden of hosting more than half of the 50,000 US troops stationed in Japan, oppose the plan which would relocate the US base to another part of the island.

According to Japanese media, the possible transfer of Marines to Guam may compromise Tokyo's position because Japanese government officials had used it as leverage to convince Okinawa to accept the base relocation.