Japan’s seawater near nuclear plant shows high radioactive levels (VIDEO)

Amid a worrying rise in radioactivity at Japan's stricken nuclear plant, tests of seawater adjacent to the plant showed radiation levels 1,250 times higher than the safety limit.

Japanese officials took samples Friday morning from a monitoring station 330 meters off the coast. The samples contained levels of radioactive iodine more than 12 times higher than the previous day, CNN reports.

An official with the plant operator, Tokyo Electric Power Co., said the high levels of radioactive iodine suggest there was some leakage directly into the ocean, CNN reports.

Drinking such seawater could be dangerous, but an adverse affect on aquatic life is unlikely, according to Japan's nuclear agency.

"Generally speaking, radioactive material released into the sea will spread due to tides, so you need much more for seaweed and sea life to absorb it," spokesman Hidehiko Nishiyama told a news conference, according to BBC. "And, since [the iodine] has a half-life of eight days, by the time people eat the sea products its amount is likely to have diminished significantly."

The operator of the Fukushima Dai-ichi plant made plans to shift from using seawater to freshwater Saturday as it tries to cool down its overheated nuclear facility, the AP reports.

Workers have been pumping seawater into the plant to stabilize its reactors after an earthquake and tsunami hit Japan March 11 and knocked out the plant's cooling system. Due to concerns over the potential for the salt in the seawater to be corrosive, the plant will now try freshwater.

U.S. naval barges loaded with freshwater were dispatched to Fukushima on Saturday, AP states. The water injections will begin early next week.

Engineers have been working for more than two weeks to bring the plant, located 140 miles northeast of Tokyo, under control.

The efforts hit a setback this week as more damage was found at the plant. Japanese officials said they fear the core of one of the reactors may have cracked and could be leaking high levels of radiation.

Experts said that a much larger release of radioactive contaminants could lead to the contamination of groundwater, according to AP.

Concerns were growing over No. 3 reactor — one of six units damaged by the double disaster — after workers were exposed to water containing 10,000 times the expected radiation levels, CNN reported earlier.

Nishiyama, the nuclear agency spokesman, told reporters Friday that it was possible the unit’s containment vessel had been damaged, raising questions over safety procedures in place to protect those working to avert disaster at the plant.

''At present, our monitoring data suggest the [reactor] retains certain containment functions, but there is a good chance that the reactor has been damaged,'' he said, according to Kyodo News.

Two workers were hospitalized after coming into contact with the radioactive water. The BBC said there were reports that the men had not been wearing the correct protective boots and had ignored a radiation alarm at the plant.

It said an inquiry was under way into safety procedures.

Many of the workers risking their lives to get the plant under control and avert a larger nuclear accident are subcontractors of the Tokyo Electric Power Co. and earn a small daily wage in exchange for working long hours in dangerous conditions, the New York Times reports.

As work continued to cool the over-heating reactors, Japanese authorities widened the area around Fukushima in which they were recommending residents to evacuate.

Government spokesman Yukio Edano said the advice to people living within 12 to 18 miles of the power station was not linked to safety, but due to concerns over “access to daily necessities,” Kyodo reported.

However, he said the continued nuclear threat could lead to mandatory expansion of the exclusion zone.

"It is desirable that they voluntarily evacuate. I cannot rule out the possibility that the government will issue an evacuation order for this area if the radiation level goes up further,” he said.

Tepco, the power plant's operator, on Friday warned that the operation to stabilize Fukushima could take more than a month.

"We are still in the process of assessing the damage at the plant, so we can't put a deadline on when the cooling operations will work again. It may take more than a month, who knows," a Tepco spokesman told Agence France-Presse.

The official death toll from the March 11 quake and tsunami has reached 10,035 with 17,443 missing.

— Hanna Ingber Win, Barry Neild