SEOUL -- A group of South Korean activists on Thursday condemned Japan's dumping of nuclear-contaminated wastewater from the crippled Fukushima Daiichi nuclear power plant into the Pacific Ocean.

The activists held a press conference near the Japanese Embassy in Seoul, urging the Japanese government to immediately stop the "nuclear terrorism crimes against humanity."

They said in a statement that the Japanese government is untrustworthy as the first round of the wastewater release has already caused trouble in the ocean, noting that the discharge is planned to continue for over 30 years.

The activists called on Japan to decommission the Fukushima nuclear power plant in cooperation with other countries and store the wastewater on its land, urging the South Korean government to file a complaint against Japan with the International Tribunal for the Law of the Sea.

Despite mounting concerns and opposition at home and abroad, Japan launched the second round of discharge of nuclear-contaminated wastewater into the ocean earlier in the day that would continue over 17 days to dump 7,800 tons of the wastewater. The first release ended on Sept 11.