Tokyo Electric Power Co. reportedly found radioactive substances in a drainage ditch that leads directly to the Pacific Ocean near the Fukushima No. 1 nuclear plant.
Tepco found the substances radiating 220 becquerels per liter in samples taken from a ditch about 150 meters from the sea and the company suspects the water seeped through sandbags placed there.
According to Japan Times, workers have been trying to decontaminate the upstream ditch for several days, which is near a water tank in the area known as H4 from which around 300 tons of highly toxic water was recently found to have leaked.
The latest findings could undermine Prime Minister Shinzo Abe's remarks made last week that the radioactive leakage has been 'completely confined'.
Tepco said that it has not taken measures to prevent the radioactive substances in the ditch from reaching the sea, the report added.