Japan's Foreign Minister Yoshimasa Hayashi urged his US counterpart Thursday to consider restricting American troop movement in the country after a surge in Covid cases on bases and surrounding communities.

The request to US Secretary of State Antony Blinken comes as virus cases surge in Okinawa, which hosts most of the US forces in Japan and is now seeing a rise in community infections.

The region's governor has blamed the rise in local cases on the clusters first seen among US troops.

Okinawa will request that the central government authorise new virus restrictions, its governor said, after the southern island region reported 623 cases on Wednesday -- nearly triple the previous day's figure.

In a call with Blinken, Hayashi "strongly requested the strengthening of measures to prevent an expansion in infections", Japan's foreign ministry said in a statement Thursday.

Hayashi called on Blinken to "consider restricting outings (by US troops) to ease worries among local residents, given the situation of coronavirus infections among US forces in Japan".

US Forces Japan said in a statement Thursday it has tightened anti-infection measures at its bases nationwide, including mask mandates on and off base and requiring a negative test for trips outside.

It added that it "now requires no less than three negative Covid-19 tests upon travelling to Japan" including immediately on arrival.

"We recognise we all have a part to play in keeping our communities safe," it said.

Okinawan officials say the US military reported 998 infections between December 15 and January 5 on bases, a figure that includes military personnel and their families, as well as contractors, but not local residents working for the US military.

Infections among US force members are not included in Okinawa's daily case reports, although cases among local Japanese staff on the bases are.

Okinawa governor Denny Tamaki has previously criticised the US military for failing to adhere to Japan's strict measures for overseas arrivals, and last month Hayashi expressed "strong regret" to the commander of US forces in Japan over the growing number of virus cases.

Hayashi said then that the US military was not adhering to Japan's policy of testing incoming travellers for the virus on arrival, and requiring them to quarantine for two weeks.

Since the complaint, US soldiers are now being tested within 24 hours of arrival, according to Tokyo.

In other parts of Japan, US bases have also reported a surge in infections in recent weeks.

Overall, Japan's infection rate remains comparatively low, with just over 2,600 cases reported nationwide on Wednesday.

But the numbers are rising, and Wednesday marked the first time that more than 2,000 cases have been reported in Japan since September.