The operators of the tsunami-stricken Fukushima nuclear power plant said Thursday they had passed an industrial camera into one of the wrecked reactors, in their first attempt to directly check the interior.

Tokyo Electric Power Co. (TEPCO) said it had managed to derive some new information from the first images taken by the endoscope in the survey at the Fukushima Daiichi nuclear power plant.

"The visual artifacts provoked by the high level of radiation and other leaks inside are a viewing obstacle, but nevertheless the images are of relatively good quality in some areas," TEPCO official Junichi Matsumoto said.

The survey aimed to check the level of cooling water inside the reactor, as well as the temperature.

"The amount of water appears to be less than what has been estimated up to now," Matsumoto said.

However, the temperature, 44.7 degrees Celsius (112.5 degrees Fahrenheit), was close to that taken at the same time by the usual measuring instruments.

Fukushima's reactor two, one of the three that went into meltdown, was chosen because it was the most suitable for such an untested operation, during which the camera recorded some 30 minutes of images.

"In reactor number three the level of radioactivity is currently too high for this kind of activity," Matsumoto added.

As well as laying waste to vast stretches of coastline in Japan's northeast, wiping out towns and destroying communities, the March 11 tsunami that followed a huge undersea earthquake, knocked out cooling systems at the Fukushima plant.

Reactors were sent into meltdown and radioactive materials leaked into the air, soil and the sea in what was the world's worst nuclear accident in a quarter of a century.