Japan's central government started main reclamation work Friday at a disputed U.S. military base relocation site on the southern island of Okinawa despite fierce local opposition.

Construction workers started dumping a truckload of sediment into the sea at Henoko on Okinawa's east coast to build a runway for a Marine Corps base that will be relocated from densely populated Futenma in the southern part of the island. The central government has reversed Okinawa's earlier ban on landfill work at the site.

Opponents of the relocation say it would not only be an environmental debacle but also ignore local wishes to remove the base.

"I strongly resent the construction that is being carried out while ignoring the will of the Okinawan people," Okinawa Gov. Denny Tamaki told reporters. He said he had repeatedly visited Tokyo and asked top officials in Prime Minister Shinzo Abe's Cabinet to postpone the landfill work and engage in dialogue. Tamaki was in Tokyo on Thursday for talks with Defense Minister Takeshi Iwaya.

Dozens of people in rubber boats protested the move. Many Okinawans say the presence of so many U.S. troops on the island is already a heavy burden and they want the existing Futenma air station closed and its replacement moved off the island entirely.

Officials in Tokyo said they will stick with the plan despite protests. Washington's position is that the dispute should be resolved between Tokyo and Okinawa.

About half of the 50,000 U.S. troops are based in Japan under a bilateral security pact and the majority of their key facilities are on Okinawa. Residents have long complained about base-related noise, pollution and crime.