TOKYO, Dec. 13 (Xinhua) -- A high court in Japan's Okinawa upheld on Thursday a lower court's ruling that found a major anti-U.S. military base activist guilty of several criminal offenses committed during protests against the U.S. base relocation plan.

The Naha District Court ruled in March that Hiroji Yamashiro was guilty of obstructing the U.S. base relocation work for piling blocks at the gate of U.S. Marine Corps' Camp Schwab and cutting barbed wire there in 2016.

He was also found guilty of injuring a local Japanese defense bureau official near a U.S. military training site in 2016.

The 66-year-old activist was sentenced to two years in prison, suspended for three years, by the local court.

His lawyers, however, said that he should be acquitted of all charges except for property damage, saying that he was "merely expressing his opposition under the freedom of expression guaranteed by the constitution."

The Naha branch of the Fukuoka High Court rejected Yamashiro's appeal, saying that the construction work was disrupted "beyond the scope of the freedom of expression."

Okinawa hosts the bulk of U.S. bases in Japan while accounting for only 0.6 percent of the country's total land mass. Criminal cases involving U.S. military men repeatedly happened there.

The Japanese and U.S. governments have been seeking to move the Futenma base from Ginowan to the less-populated Henoko coastal area of Nago. The people of Okinawa, however, demand the Futenma base to be relocated outside the prefecture.