TOKYO - The president of the utility that owns Japan's tsunami-damaged nuclear complex was hospitalized with hypertension as setbacks mounted at the plant, where experts Wednesday logged the highest radiation yet in nearby seawater.

Masataka Shimizu, president of Tokyo Electric Power Co., has not been seen for nearly two weeks after appearing at a Tokyo news conference two days after the March 11 earthquake and tsunami that hobbled the Fukushima Dai-ichi plant's cooling systems and set off radiation leaks.

Shimizu, 66, was taken Tuesday to a Tokyo hospital after suffering dizziness and high blood pressure, TEPCO spokesman Naoki Tsunoda said.

There had been much speculation about Shimizu's health since he disappeared from public view, with company Vice President Sakae Muto appearing instead at news briefings. TEPCO officials had deflected questions about Shimizu's health, saying he was "resting" at company headquarters.

It was the latest crisis to beset TEPCO, still struggling to stabilize the dangerously overheated power plant and to contain the radiation seeping from the complex and into the sea and soil nearby. The magnitude-9.0 quake spawned a tsunami that knocked out power and backup systems crucial to keeping temperatures down inside the plant's reactors and spent fuel pools.

Residents within 20 kilometers of the plant were evacuated two weeks ago, while those up to 30 kilometers have been urged in recent days to leave voluntarily.

Elevated levels of radiation, meanwhile, has turned up in vegetables, raw milk and water. Last week, tap water as far away as Tokyo, 220 kilometers to the south, contained levels of cancer-causing iodine-131 considered unsafe for infants.

On Wednesday, nuclear safety officials said seawater outside the plant was found to contain 3,335 times the usual amount of radioactive iodine — the highest rate yet and a sign that more contaminated water was making its way into the ocean.

The amount of iodine-131 found offshore some 300 meter south of the plant does not pose an immediate threat to human health but was a "concern," Hidehiko Nishiyama, a Nuclear and Industrial Safety Agency official, said Wednesday.

He said there was no fishing in the area.

"We will nail down the cause, and will do our utmost to prevent it from rising further," he said. Nishiyama has previously acknowledged that some contaminated water from the plant was seeping into the sea, but it remains unclear what part of the plant is leaking.

Highly toxic plutonium also has been found seeping into the soil outside the plant, TEPCO said. Safety officials said the amounts did not pose a risk to humans, but the finding supports suspicions that dangerously radioactive water is leaking from damaged nuclear fuel rods.

The latest findings on radioactive iodine — based on a sample taken Tuesday afternoon — highlight the urgency of stabilizing the crippled power plant. The mission has been fraught with setbacks, as emergency crews have dealt with fires, explosions and radiation scares in the frantic bid to prevent a complete meltdown.

Workers succeeded last week in reconnecting some parts of the plant to the power grid. But as they pumped in water to cool the reactors and nuclear fuel, they discovered numerous pools of radioactive water, including in the basements of several buildings and in trenches outside.

The contaminated water has been emitting many times the amount of radiation that the government considers safe for workers. It must be pumped out before electricity can be restored and the regular cooling systems powered up.

That has left officials struggling with two crucial but contradictory efforts: pumping in water to keep the fuel rods cool and pumping out contaminated water.

Prime Minister Naoto Kan reiterated in a speech this week to parliament that Japan was grappling with its worst problems since World War II.

More than 11,000 bodies have been recovered, but officials say the final death toll is expected to exceed 18,000. Hundreds of thousands of people remain homeless, their homes and livelihoods destroyed. Damage could amount to $310 billion — the most expensive natural disaster on record.

Kan has faced increasing criticism from opposition lawmakers over the handling of a nuclear disaster stretching into a third week.