Japan's government has violated the rights of Okinawa's residents for decades by allowing a heavy presence of American troops on the tiny southern island, Okinawa's governor told a court hearing Wednesday, the start of a legal battle over plans to relocate a U.S. air base.

The dispute over the air base escalated into a legal battle after Japan's government filed a lawsuit against Okinawan Gov. Takeshi Onaga, seeking to overturn his cancellation of an earlier local approval for land reclamation needed for the base's relocation.

The long-stalled plan would move the U.S. Marine Air Station Futenma from a densely populated neighborhood to the island's seaside Henoko Bay. But many residents want the base moved out of the prefecture and have picketed the area, trying to prevent construction equipment from entering.

Onaga said in court on Wednesday that the lawsuit is not just about the legality of his revocation of the land reclamation approval, but about democracy and Okinawans' human rights, according to the text of his statement.

About 74 percent of the space used by the U.S. military in Japan is concentrated on Okinawa, which is only 0.6 percent of Japan's land area.

"Do local autonomy and democracy really exist in Japan? The current national security forces the burden (of hosting U.S. bases) on Okinawa alone. Is it normal? I want to ask all Japanese people," he said at the hearing, held in Okinawa's prefectural capital of Naha.

Onaga noted that following Japan's defeat in World War II, U.S. occupation forces confiscated land from residents on Okinawa, and that the island was under U.S. occupation until 1972, 20 years longer than the rest of Japan. He said that Okinawans' will is still neglected, now by Japan's government.

Onaga was elected last year, widely supported by voters who feel Okinawa bears an unfair burden of the U.S. military presence. His anti-base stance has also made residents of Okinawa, an island with a distinct culture, more aware of their identity.

Tetsuya Takahashi, a University of Tokyo professor and expert on the Okinawa base issue, said the lawsuit underscores Tokyo's "colonial-style" approach to Okinawa and could only deepen the divide. "The central government is apparently waiting for Okinawans to give up, but they won't. The dispute could even escalate," he said.

Lawyers representing the central government said Onaga's cancellation of the earlier approval is illegal, arguing that his action would prolong the risk from the Futenma base and harm Japan-U.S. relations and Tokyo's national interests, according to Kyodo News agency.

Chief Cabinet Secretary Yoshihide Suga told reporters in Tokyo that Onaga's predecessor had properly issued the reclamation approval. "It is extremely regrettable we had to go to court," he said.

Some critics of the landfill plan also object to potential environmental damage to the previously undeveloped Henoko shore.

Television video showed hundreds of people -- clapping and shouting "Onaga, Onaga" -- gathering outside the courthouse Wednesday morning hoping to be among the dozens of observers to get a seat inside.

Tokyo briefly suspended the reclamation work earlier this year while seeking a compromise with Onaga, but has since overridden local objections to resume the work.