TOKYO — Fueled by speculation that the government seeks to move Marine air units off their island and then back again, Okinawans brought their protests to Tokyo this week.

According to Japanese press accounts quoting unnamed sources, Prime Minister Yukio Hatoyama’s plan is to close Marine Corps Air Station Futenma as soon as possible by moving air operations to Tokunoshima, a small island in Kagoshima Prefecture 125 miles north of Okinawa, while an airport is constructed on a man-made island in waters off the Katsuren peninsula, near the U.S. Navy’s White Beach port.

Hatoyama on Monday called the reports “groundless speculation,” but the protesters were not deterred.

About 150 people from Okinawa and the mainland were joined by some lawmakers as they began a four-day sit-in Tuesday at Japan’s Diet building.

Meanwhile, two other groups from Okinawa met with government officials and local supporters in their push to get Futenma closed and its air units moved permanently off the island.

Yoshiyasu Iha’s group of Uruma residents took aim at the rumored plan during a meeting of anti-base supporters in Tokyo on Wednesday. White Beach is within Uruma’s city limits.

An artificial island will have a severely negative effect on the livelihoods of fishermen and seaweed harvesters, he said.

A third group was led by Yoshikazu Tamaki, speaker of the Okinawa Prefectural Assembly, which passed a unanimous resolution last month against any new base on Okinawa. Tamaki was the guest speaker at a separate rally billed as an “Emergency Meeting of Okinawa Solidarity” held at a union hall in Tokyo’s Chiyoda ward.

Tamaki said the national government should also reexamine the U.S.-Japan Security Treaty, according to the Okinawa Times, asking the crowd: “Do we really need Marines on Okinawa?”