The Okinawa Defense Bureau and the city of Okinawa uncovered seven more barrels Tuesday at a former U.S. military installation in the prefecture that may have been used to hold toxic chemicals during the Vietnam War, stoking concern among residents.

Prior to Tuesday's findings, the city had dug up 19 barrels from the same site in mid-June.

The barrels found Tuesday had been buried about 1 meter deep in a soccer ground adjacent to the Kadena Air Base that had been part of the installation until 1987, the Defense Ministry said.