Japan's earthquake-hit nuclear complex is still emitting radiation but the source is unclear, said James Lyons in Vienna Tuesday, a senior official of the International Atomic Energy Agency.

Senior IAEA official Graham Andrew said that the overall situation remained "very serious."

"We have not received validated information for some time related to the containment integrity of unit 1.

So we are concerned that we do not know its exact status," he said. The IAEA also lacks data on the temperatures of the spent fuel pools of reactors 1, 3 and 4, he said. Japanese technicians have attached power cables to all six reactors and started a pump at one to cool overheating nuclear fuel rods.

Away from the plant, mounting evidence of radiation in vegetables, water and milk stirred concerns in Japan and abroad despite officials' assurances that the levels were not dangerous.