South Korea's foreign ministry called in a Japanese Embassy official Thursday to express concerns over the operator of Tokyo's crippled Fukushima nuclear power plant having filed for approval for its planned release of radioactive water into the ocean.

On Tuesday, Tokyo Electric Power Co. (TEPCO) submitted an application for the planned water release to Japan's Nuclear Regulation Authority (NRA) amid growing concerns in South Korea that it could cause health risks and maritime contamination.

Lee Tong-q, the ministry's director general for climate change, energy, environmental and scientific affairs, delivered Seoul's concerns in a diplomatic document to Daisuke Namioka, minister of economic affairs at the Japanese Embassy in Seoul.

In April, Japan announced a plan to start discharging the radioactive water into the sea in 2023 in what is expected to be a decadeslong process, as all storage tanks at the Fukushima plant are expected to be full as early as fall of 2022.

An estimated 1.25 million tons of such water are in temporary storage at the Fukushima nuclear plant on the east coast of Japan, which was hit by a tsunami in the wake of an earthquake in March 2011. (Yonhap)