Around 600 protesters staged a rally at the relocation site for the contentious U.S. Marine Corps Air Station Futenma in Okinawa Prefecture on Wednesday, one year after construction work began there.

The protesters staged a sit-in in front of a gate at the neighboring U.S. Marine Corps' Camp Schwab and paddled their canoes on waters surrounding the building site in the prefecture's northeastern city of Nago, with some raising placards saying, "U.S. Marine Corps, get out of Okinawa."

Local police forcefully moved aside some 400 protesters who had gathered at the gate to block vehicles entering the base for construction work.

"Why does the central government build a new base in Okinawa as we oppose (its construction) like this," said protester Toshiko Uema, 70.

In late April last year, the government began building seawalls in preparation for the controversial relocation plan to transfer the Futenma air base, now in a crowded residential area in Ginowan, to Henoko, a small coastal area of Nago next to Camp Schwab.

A Kyodo News helicopter confirmed Tuesday the seawall surrounds an area where the government plans to reclaim land to build a new facility starting in July.