Smoke rose Thursday from the world's largest nuclear power plant in Japan, which was hit by a deadly earthquake two years ago, but the operator said no-one was injured and there was no radiation leak.

"A worker at our company spotted smoke emerging from the brake of the hoisting function of a crane in a turbine room," the operator Tokyo Electric Power Co. (TEPCO) said in a statement.

"We reported immediately to the fire station and used fire extinguishers and now the smoke has stopped."

"There were no injuries nor any radiation leak" resulting from the incident in the Kashiwazaki-Kariwa nuclear plant, in Niigata prefecture, 200 kilometres (125 miles) north of Tokyo, it said.

The company said it would thoroughly investigate.

Kashiwazaki city was rocked by a 6.8-magnitude earthquake in July 2007. The epicentre was just 16 kilometres from the plant, where a fire started and a small amount of radiation leaked out.

Local residents have voiced fears over the safety of the plant following a string of fires there as well as concerns raised by some geologists that an off-shore tectonic faultline could trigger stronger earthquakes in future.

Japan, the world's second largest economy but with virtually no energy deposits of its own, relies on nuclear power for about one-third of its electricity demand and aims to boost the figure to 40 percent by 2010.