Two U.S. Marine bases in Okinawa Prefecture have been put on lockdown by the military, with 62 coronavirus cases confirmed last week, the prefectural government said.

U.S. forces told the Okinawa government the cases were confirmed between Tuesday and Saturday at U.S. Marine Corps Air Station Futenma and Camp Hansen, and the two bases had been locked down, prefectural government officials said.

Lt. Gen. Stacy Clardy, commander of the III Marine Expeditionary Force and head of U.S. forces in Okinawa, explained the infection situation at the military facilities to Gov. Denny Tamaki by phone, they said.

The Marine Corps said it "experienced two localized clusters of individuals who tested positive for the virus" and that all personnel who tested positive for COVID-19, the respiratory disease caused by the virus, are in isolation.

Before the exact infection number was released, Tamaki said at a news conference that he was "shocked" by the U.S. forces' report on the new infections.

"We have strong doubts about measures (taken by the U.S. troops) to prevent the spread of the virus," he said.

Tamaki added that some American military personnel had held parties in downtown areas and beaches around July 4 to celebrate the U.S. Independence Day and called on participants in such events to see a doctor if they feel unwell.

Kadena Air Base and Camp McTureous in Okinawa have also seen coronavirus infections, according to the prefectural government.

The southern island prefecture has reported 148 coronavirus cases, excluding those of U.S. military personnel. Okinawa hosts the bulk of American military facilities in Japan.