TEPCO had previously denied suspicions that contaminated water had reached the sea, despite the fact that levels of potentially cancer-causing radioactive substances present in ground and seawater
"But now we believe that contaminated water has flown out to the sea," TEPCO spokesman Masayuki Ono said at a Monday news conference.
According to Ono, officials suspect that radioactive water leaked from the wrecked reactors, likely seeping into the underground water system before reaching the sea.
Earlier this month, TEPCO acknowledged that levels of radioactive cesium-134 in a well at the nuclear power plant jumped by 90 times in just three days. The company said the levels were at their highest point since the March 2011 disaster.
However, the company’s spokesman insisted on Monday that the radioactive water’s impact on the ocean would be limited.
"Seawater data has shown no abnormal rise in the levels of radioactivity," Ono said.
TEPCO said that based on water sample tests, the leaks stay near the plant reactors inside the bay.
The announcement has confirmed alarming concerns addressed by Japan's nuclear watchdog, the Nuclear Regulation Authoirty (NRA). Earlier in July, the organization stated that it “strongly suspected” contamination of ground waters and possibly the Pacific Ocean.
The head of NRA also said he believed that contamination of the sea has been continuous since the accident in March 2011, when a massive earthquake and tsunami triggered three meltdowns in the Fukushima plant.
"We would like to offer our deep apology for causing grave worries for many people, especially for people in Fukushima," Masayuki Ono said.