A nearly completed new power line could restore electric cooling systems in Japan's tsunami-crippled nuclear plant, its operator said Thursday, raising hopes of easing the crisis that has threatened a meltdown.

Tokyo Electric Power Co. spokesman Naoki Tsunoda said the new power line to Fukushima Dai-ichi is almost complete. Officials plan to try it "as soon as possible" but he could not say when.

Meanwhile, conditions at the plant appeared to worsen Wednesday, with white smoke pouring from the reactor complex and a dangerous surge in radiation levels forcing workers to retreat for hours from their struggle to cool the overheating reactors.

The chief of the International Atomic Energy Agency said he would go to Japan as soon as possible to assess the danger. He called the situation serious and urged the Japanese government to provide better information to the agency.

The new line would revive electric-powered pumps, allowing the company to maintain a steady water supply to troubled reactors and spent fuel storage ponds, keeping them cool. The company is also trying to repair its existing disabled power line.

The word came as international concern mounted over the deteriorating situation at the Fukushima Dai-ichi plant, where the danger from the reactors has nearly overshadowed the human tragedy of last week's magnitude 9.0 earthquake and subsequent tsunami that pulverized Japan's northeastern coast and is feared to have killed more than 10,000 people.

The 180 emergency workers have been working in shifts to manually pump seawater into the reactors because last week's earthquake and tsunami disabled main and backup power for electric-powered cooling pumps.