RIKUZENTAKATA, Japan – Highly radioactive water was leaking into the sea Saturday from a crack discovered at a nuclear power plant destabilized by last month’s earthquake and tsunami.

The contaminated water will quickly dissipate into the sea and is not expected to cause any health hazard. Nevertheless, the disturbing discovery points at the unexpected problems that can crop up and continue to hamper technicians trying to control the crisis.

Word of the leak came as Prime Minister Naoto Kan toured the town of Rikuzentakata, his first trip to survey damage in one of the dozens of villages, towns and cities slammed by the March 11 tsunami that followed a magnitude-9.0 earthquake.

“The government has been too focused on the Fukushima power plant rather than the tsunami victims. Both deserve attention,” said 35-year-old Megumi Shimanuki, who was visiting her family at a community center converted into a shelter in hard-hit Natori, about 100 miles from Rikuzentakata.

The double disaster is believed to have left nearly 25,000 dead – 11,800 confirmed. More than 165,000 are still living in shelters, and tens of thousands more still do not have electricity or running water.

Although the government had rushed to provide relief, its attention has been divided by the efforts to stabilize the Fukushima Dai-ichi nuclear plant, which suffered heavy damage and has dragged the country to its worst nuclear crisis since the atomic bombings of Hiroshima and Nagasaki during World War II.

The plant’s reactors overheated to dangerous levels after electrical pumps – deprived of electricity – failed to circulate water to keep the reactors cool.

A series of almost daily problems has led to substantial amounts of radiation leaking in the atmosphere, ground and sea. On Saturday, workers discovered an 8-inch-long crack in a maintenance pit that was leaking highly radioactive water into the Pacific Ocean, said Hidehiko Nishiyama, Japan Nuclear and Industrial Safety Agency spokesman.

He said the water contaminated with levels of radioactive iodine far above the legal limit found inside the pit could be one of the sources of recent spikes in radioactivity in seawater.

“There could be other similar cracks in the area, and we must find them as quickly as possible,” he told reporters.

Soon after the discovery, the plant’s operator, Tokyo Electric Power Co., started filling the pit with concrete to seal the crack and prevent more contaminated water from seeping into the ocean.

Nuclear safety officials said the crack was likely caused by the quake and may be the source of radioactive iodine that started showing up in the ocean more than a week ago.

People living within 12 miles of the nuclear power plant have been evacuated and the radioactive water will quickly dissipate in the sea, but it was unclear whether the leak posed any new danger to workers.

The cracked pit houses cables for one of the six nuclear reactors, and the concentration of radioactive iodine was the same as in a puddle of contaminated water found outside the reactor earlier in the week.

Because of that, officials believe the contaminated water is coming from the same place, though they are not sure where.

Radiation worries have compounded the misery for people trying to recover from the tsunami. Kan’s visit Saturday to Rikuzentakata did little to alleviate their worries.

“The government fully supports you until the end,” Kan told 250 people at an elementary school serving as an evacuation center. He earlier met with the mayor, whose 38-year-old wife was swept away.

He bowed his head for a moment of silence in front of the town hall, one of the few buildings still standing, though its windows are blown out and metal and debris sit tangled out front.