From Al Jazeera:

"The operator of Japan's Fukushima Daiichi quake-crippled nuclear complex has said a spike reported in radioactivity at the plant is a mistake.

Jiji Press quoted the Tokyo Electric Power (TEPCO) as saying on Sunday that the mistake - which indicated radiation levels 10 million times higher than normal - was due to confusion between readings of iodine and cobalt in the water.

The inaccurate reading had forced emergency workers to flee from the complex's Unit 2 reactor.

"The number is not credible," said TEPCO's 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 Daiichi complex's most troubled reactors, and as airborne radiation in Unit 2 measured 1,000 millisieverts per hour - four times the limit deemed safe by the government, Kurita said.

The plant has been crippled by an earthquake and a tsunami that devastated northeastern Japan two weeks ago, sparking fears of high levels of radiation.

Officials say they still do not know where the radioactive water is coming from, though government spokesman Yukio Edano has said some is "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 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."

Charley Noble