Monday's earthquake in Japan did, in fact, cause a leak at the nuclear power plant hit by the blast, according to plant officials.
Security authorities had denied the release of any radiation from the plant in Kashiwazaki city after the 6.8 quake, but have now confirmed that unforeseen levels of radioactive material have been discharged into the sea.
However, a statement from the Tokyo Electric Power Company (TEPCO) said: "The corrected radioactivity is also below the legal limits and does not affect the environment."
The earthquake had caused a fire at an electrical transformer, as well as the spillage of low-level nuclear waste from a number of drums.
Tsunehisa Katsumata, president of Tepco, has responded to criticism of the company's safety policies.
"I think we can say the size of the earthquake was beyond our expectations," he said. "We regret what happened and will strive to make this a power plant that is safe."
Nine people were killed by the earthquake, with some 2,000 evacuated from their homes.
When asked whether the plant might be sat on a tectonic fault line, Osamu Kamigaichi of the Japanese Meteorological Agency told AFP: "We cannot deny the possibility."
