TOKYO (AFP) - Part of the container of a troubled nuclear reactor appears to be damaged, the Japanese government said early Tuesday, indicating possible serious radiation leaks.

Chief Cabinet Secretary Yukio Edano told reporters that "damage appears on the suppression pool" -- the bottom part of the container, which contains water used to cool down the reactor and control air pressure inside.

"But we have not recorded any sudden jump in radiation indicators," Edano said without elaborating.

If confirmed, it will be the first direct damage to the reactor since a massive earthquake and tsunami battered Japan's northeast coast on Friday, knocking out nuclear plants in Fukushima, north of Tokyo.