Okinawa Gov. Takeshi Onaga said Tuesday a tumor has been found in his pancreas and he will undergo surgery.

The 67-year-old said he wants to return to official duties as soon as possible as he remains committed to strongly opposing the state's controversial plan to relocate a key U.S. military base within the prefecture with his current four-year term set to end in December.

"I want to fulfill my responsibility as governor," he said at a press conference at a hospital in Urasoe, Okinawa Prefecture.

Onaga declined to clarify whether he will run for another term, while the ruling Liberal Democratic Party is stepping up efforts to field a candidate to promote the relocation plan.

The governor canceled his recent official duties, including a trip to China, and was hospitalized last Thursday after a medical examination.

Onaga won his first election as governor in November 2014 on a platform of opposing the plan to relocate U.S. Marine Corps Air Station Futenma from the crowded residential area of Ginowan to a coastal area of Nago, saying the base should be moved out of the southern island prefecture.

The central government maintains the stance that the current plan is "the only solution" for removing the dangers posed by the Futenma base, which is situated close to schools and homes, without undermining the perceived deterrence provided by American troops under the Japan-U.S. alliance.

Onaga previously underwent surgery to remove early-stage stomach cancer in 2006 when he was the mayor of Naha, the Okinawa capital.