A recent survey conducted by the Japanese daily Yomiuri Shimbun shows about 50 percent of citizens in Japan are against their government's plan to discharge radioactive water from the tsunami-wrecked Fukushima nuclear plant into the sea.
The survey was conducted on over one-thousand eligible voters from across Japan.
Media reports say the fishing industry in Fukushima Prefecture is also opposed to the idea.
The governor of South Korea's southern island of Jeju, Won Hee-ryong held a press conference on Tuesday, saying he will bring the case to both local and international courts if Japan goes ahead with its plan.
Seoul's foreign ministry has also repeatedly voiced its concerns over the planned discharge.
"The South Korean government has been constantly emphasizing transparent information sharing and communication with the international community on the issue. We will prioritize our people's health and safety, and continue efforts based on international cooperation."
Beijing has also called on Tokyo to make a decision carefully after negotiating with its neighbors.
It pointed out that radioactive material from the 2011 tsunami and earthquake has already been discharged, posing a grave threat to the marine environment and human health.
The Japanese government is likely to officially announce its discharge plan early next week.
"We would like to deepen the discussion within the government and want to make a decision responsibly at an appropriate time."
Experts warn of the danger from a radioactive substance called tritium, which will not be completely eliminated despite a purifying process.
But some say there aren't many realistic measures to prevent Japan from discharging the contaminated water.
Sources say the South Korean government is currently focused on pressuring Japan to discharge it transparently and safely so the international community can, at the least, feel less concerned.
Yoon Jung-min, Arirang News.