Tests of seawater near Japan’s Fukushima nuclear power plant have not detected any radioactivity, the environment ministry said on Sunday (Aug 27), days after authorities began discharging into the sea treated water used to cool damaged reactors.

Japan started releasing water from the wrecked Fukushima plant into the Pacific Ocean on Thursday, sparking protests within Japan and neighbouring countries, in particular China, which banned aquatic product imports from Japan.

Japan and scientific organisations say the water is safe after being filtered to remove most radioactive elements except for tritium, a radioactive isotope of hydrogen.