Japan went a step further on Monday toward its nuclear-contaminated water release plan, as Tokyo Electric Power Company, operator of the crippled Fukushima Daiichi nuclear power plant, finished removing the heavy machinery used for digging an ocean tunnel.

The underwater tunnel has been built to release more than 1.3 million metric tons of treated but still radioactive water into the Pacific Ocean. The toxic water has been used to cool the highly radioactive, damaged reactor cores, and there is enough of it to fill 500 Olympic-size swimming pools.

According to Fukushima Central Television, preparations for releasing the contaminated water into the ocean will be almost complete once the discharge port is covered.

Intensified protests

The move also came at a time when Japan's unilateral decision provoked intensified protests from neighboring countries, Pacific Island communities and civil society groups in the most affected prefectures such as Fukushima, Iwate and Miyagi.

On Monday, the Republic of Korea's opposition Justice Party held a news conference in front of the Japanese embassy after the party's floor leader Bae Jin-gyo made a three-day trip to Japan last week, including a visit to the nuclear plant.

Members of the party's special task force opposing the release met with local civic groups in Japan and held a press conference at TEPCO to deliver their objections, but their letter of complaint to TEPCO was rejected.

On Thursday, the Japan Fisheries Cooperatives reiterated their opposition to the discharge in a resolution, though the Japanese government proposed a 50 billion yen ($349 million) package to buy their "understanding".

"We remain firmly opposed to discharging the water," the resolution said.

"We are by no means saying it's OK to discharge the water," Masanobu Sakamoto, head of the cooperative, said.

Koji Suzuki, head of a fishery company who organized the session, said he opposes the plan. Stakeholders in the industry, who continue to wait for an explanation of the release plan, need additional information that can be shared with customers who doubt the safety of seafood.

Also on Thursday, Japan was urged to face up to the legitimate concerns of the international community on the dumping of nuclear-contaminated water into the ocean at the 53rd session of the United Nations Human Rights Council. The Chinese representative at the session said Japan's move violated its obligations under the UN Convention on the Law of the Sea.

Kalinga Seneviratne, a visiting lecturer at the University of the South Pacific, said Japan should respect the South Pacific Nuclear Free Zone Treaty, inked by Pacific Islands Forum members in 1985, which explicitly prohibits activities such as testing, manufacturing and stationing nuclear explosive devices and dumping nuclear waste within the zone.

Xinhua contributed to this story.