Japan's military says it does not plan further helicopter air drops of water on overheating reactors at the tsunami-ravaged nuclear plant.

Defence Ministry spokesman Ippo Mayama said on Friday that further helicopter runs were not planned, following several runs the day before. He did not say why. It was unclear of what effects the water drops had on the targeted reactor.

Smoke rises from nuclear plant

Japan’s nuclear safety agency says smoke is rising from a building housing a damaged nuclear reactor at a power plant crippled by last week’s tsunami.

A spokesman for Japan’s nuclear safety agency said the smoke was seen rising from Unit 2 at the Fukushima Dai-ichi plant on Friday morning. The spokesman says the agency does not know the cause, but an explosion occurred in Unit 2 earlier in the week, possibly damaging a chamber next to the reactor core.

Meanwhile, the utility that runs the nuclear plant says workers are laying a cable to restore power to the cooling systems. The military is also preparing to spray more water on the plant by helicopter and fire trucks.