The International Atomic Energy Agency on Monday called on the operator of Japan's crippled Fukushima nuclear plant to improve "essential systems" as it struggles to deal with leaks and power cuts. The stricken site has suffered an increasingly long line of mishaps, including a series of radioactive water leaks, that have rattled public confidence in the aftermath of the worst atomic crisis in a generation.

"TEPCO (Tokyo Electric Power) should continue its efforts to improve the reliability of essential systems, to assess the structural integrity of site facilities and to enhance protection against external hazards," the UN nuclear watchdog said in a statement.