The operator of a crippled nuclear plant in Japan has retracted an announcement that radiation in water near one of the reactors was 10 million times higher than normal, Jiji Press reports.
Tokyo Electric Power (TEPCO) said the mistake was due to confusion between readings of iodine and cobalt in the water.
Earlier TEPCO said radiation of more than 1000 millisieverts per hour had been detected in puddles of water thought to have leaked from the the number two reactor at its Fukushima Daiichi plant.
It did not retract that figure.
TEPCO employees had fled the complex's Unit 2 reactor when a reading showed radiation levels had reached 10 million times higher than normal in the reactor's cooling system.
Officials said they were so high the worker taking the measurements had withdrawn before taking a second reading.
Plant operators said today that while the water was contaminated with radiation, the extremely high reading was a mistake.
"The number is not credible," said TEPCO spokesman Takashi Kurita. "We are very sorry."
He said officials were taking another sample to get accurate levels, but did not know when the results would be announced.
The situation came as officials acknowledged there was radioactive water in all four of the Fukushima Dai-ichi complex's most troubled reactors, and as airborne radiation in Unit 2 measured 1000 millisieverts per hour - four times the limit deemed safe by the government, Kurita said.
Officials say they still did not know where the radioactive water was coming from, although government spokesman Yukio Edano has said some was "almost certainly" seeping from a cracked reactor core in one of the units.
While the discovery of the high radiation levels - and the evacuation of workers from one reactor unit - again delayed efforts to bring the deeply troubled complex under control, Edano insisted the situation had partially stabilised.
"We have somewhat prevented the situation from turning worse," he told reporters on Sunday evening.
"But the prospects are not improving in a straight line and we've expected twists and turns. The contaminated water is one of them and we'll continue to repair the damage."
The discovery over the last three days of radioactive water has been a major setback in the mission to get the plant's crucial cooling systems operating more than two weeks after a massive earthquake and tsunami.
The magnitude-nine quake off Japan's north-east coast on March 11 triggered a tsunami that barrelled onshore and disabled the Fukushima plant, complicating an immense humanitarian disaster.
The death toll from the twin disasters stood at 10,668 on Sunday, with more than 16,574 people missing, police said. Hundreds of thousands of people are homeless.
Workers have been scrambling to remove the radioactive water from the four units and find a safe place to store it, TEPCO officials said.
On Sunday night, Minoru Ogoda of Japan's nuclear safety agency said each unit could have hundreds of tonnes of radioactive water.