The president of the company that owns Japan's stricken Fukushima nuclear power station has been taken to hospital.
Masataka Shimizu, who is reportedly suffering from dizziness and high blood pressure, has not been seen in public since a press conference held two days after the March 11 earthquake.
The disaster shut down the plant's cooling systems and set off a series of radiation leaks.
Prior to him being taken to hospital, spokespeople from TEPCO - the company behind the Fukushima reactors - had told journalists inquiring about Shimizu's whereabouts that he was "resting".
Shares in TEPCO are now worth around a fifth of their pre-earthquake value, and despite securing £15bn in loans, the company may still have to be taken over by the government.
TEPCO will likely face a mammoth compensation bill after revelations that its management ignored safety warnings about the Fukushima power station.
The company is also accused of concealing information during the crisis. A spokesman has denied it, but admitted "various mistakes and delays in the timing of making announcements".
Efforts to contain the overheating reactors have been hampered by several fires and explosions, while more than a dozen of the workers struggling to restart the plant's cooling systems have been injured.
Mr Shimuzu's hospital treatment comes as Japanese officials acknowledge for the first time that nuclear safety standards were insufficient before the earthquake.
The ministry in charge of the nuclear industry now plans to draw up new rules for power plant operators.
Radioactive leakage has already tainted Tokyo tap water, as well as milk and produce from the Fukushima region.
Soil samples close to the plant have also shown traces of plutonium - a radioactive and highly toxic substance used in atomic weapons.
French nuclear power experts have flown in to help TEPCO try to contain the overheating reactors.
And the US has lent Japan robots previously used in Iraq and Afghanistan that can be used to navigate, film and clear rubble inside the contaminated plant.