TOKYO - The operator of Japan's stricken Fukushima nuclear power plant, said on Saturday it had suspended an operation to clean up radioactive water only hours after it had begun as radiation levels rose faster than expected.

"The level of radiation at a machine to absorb caesium has risen faster than our initial projections," said a spokesman for Tokyo Electric Power Co .

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The plan had got underway on Friday after being delayed by a series of glitches.

Officials had said earlier this week that large and growing pools of radiactive water at the Fukushima Daiichi plant were in danger of spilling into the sea within a week unless action was taken quickly.

Tepco has pumped massive amounts of water to cool three reactors at the plant that went into meltdown after the March 11 earthquake and tsunami disabled cooling systems.

But managing the radioactive water has become a major headache as the plant runs out of places to keep it. Around 110,000 tonnes of highly radioactive water is stored at the plant.