The head of the world's nuclear watchdog agency has warned that Japan was still far from the end of the accident that struck its Fukushima nuclear complex. Director General of the International Atomic Energy Agency, Yukiya Amano, said Japanese authorities were still unsure about whether the reactor cores and spent fuel were covered with the water needed to cool them. Amano said he saw a few positive signs, with the restoration of some external electric power to the plant. But he added that more efforts should be done to put an end to the accident. He warned that the nuclear emergency could go on for weeks, if not months, given the enormous damage to the plant. Amano, a former Japanese diplomat who took over the IAEA in late 2009, said his biggest concern was the spent fuel rods sitting in open cooling pools atop the reactor buildings.