TOKYO >> Japan’s respected emperor visited the country’s earthquake- and tsunami-ravaged disaster zone for the first time Thursday as frustration rose over the nation’s inability to gain control over a crisis at a nuclear plant crippled by the twin disasters.

Even as the month-old emergency dragged on, radiation levels dropped enough for police sealed in white protective suits, goggles and blue gloves to begin searching for bodies amid the muddy debris inside a six-mile radius around the Fukushima Dai-ichi plant that had been off-limits.

Authorities believe up to 1,000 bodies are lodged in the debris. Overall, the bodies of only about 13,500 of the more than 26,000 people believed killed in the March 11 disaster have been recovered.

In Asahi, where 13 people were killed and some 3,000 homes damaged, Emperor Akihito and Empress Michiko got their first look at the devastation, somberly gazing at a plot of land where a home once stood and commiserating with evacuees at two shelters.

The royal couple kneeled on mats to speak quietly with the survivors, who bowed in gratitude and wiped away tears. One evacuee with Down syndrome, who has trouble speaking, wrote “I will keep striving” in a small notebook that he showed to the emperor and empress. Asahi is about 55 miles east of Tokyo.

Nearly 140,000 people are still living in shelters after losing their homes or being advised to evacuate because of concerns about radiation.

Akihito, 77, has been active in trying to console the nation since the disasters struck last month. He made an unprecedented made-for-TV address expressing his condolences and has visited evacuees relocated to Tokyo. He is expected to visit other tsunami-affected areas of Japan’s northeast coast in coming weeks.

Meanwhile, the nuclear impasse is compounding the political difficulties of Prime Minister Naoto Kan.

In recent days, opposition politicians — who refrained from heavy criticism in the initial weeks after the disaster — have resumed calls for his resignation, and some critics have called for independent inquiries into the handling of the crisis.

On Thursday, an expert panel appointed by the government began discussing reconstruction plans and compiling recommendations.

“We may not be able to provide technical advice on how to resolve the nuclear accident. But what’s important is that the discussion involves the entire nation,” said Defense Academy chief Makoto Iokibe, who heads the 15-member panel and urged a careful revision of safety standards.

Yoshihisa Kato, a 66-year-old noodle shop owner, said he had been going to funerals nearly every day for elderly neighbors who died from the stress and exhaustion.

“I am physically and mentally worn out by the nuclear crisis,” said Kato, whose shop is in Kawamata, a town about 30 miles northwest of the plant. He called the government and the nuclear plant operator, Tokyo Electric Power Co., or TEPCO, liars for promising support and money for those affected.

“They have done nothing so far to help us,” said Kato, adding that he planned to ignore government recommendations to evacuate his town, despite warnings over risks from elevated radiation levels.

Japan acknowledged this week that the overall amount of leaked radioactivity already has catapulted the crisis to the highest level on an international scale. That puts it on a par with Chernobyl, though Japan’s crisis still involves only a tenth of the radioactivity emitted in the 1986 disaster.

Although Japanese officials have insisted the situation at the crippled plant is improving, the crisis has dragged on, punctuated by a nearly nonstop series of mishaps and aftershocks of the 9.0-magnitude quake that have impeded work in clearing debris and restoring the plant’s disabled cooling systems.

Officials acknowledged Thursday yet another glitch in efforts to cool the used fuel at the plant.

Water inadvertently sprayed into an overflow tank at one of the compound’s pools for spent fuel rods and led to a false reading that the main pool was full when it wasn’t. That prompted workers to suspend the injection of water into the main pool for several days until Wednesday, when spraying resumed.

Strong aftershocks might also have affected the readings, officials said.

The suspension of spraying allowed temperatures and radiation levels to rise, though the rods were still believed to have been covered with water, said Hidehiko Nishiyama of Japan’s Nuclear and Industrial Safety Agency.

“I believe fuel rods in the pool are largely intact, or still keeping the normal shape of what they should look like,” Nishiyama said. “If they were totally messed up, we would have been looking at different sets of numbers from the water sampling.”

Three of the plant’s reactor buildings also have about 22,000 tons (20,000 metric tons) each of stagnant, radiation-contaminated water and it is proving difficult to reduce the amount spilling from the reactors, Nishiyama said.

Until cooling systems can be fully restored, flooding the reactors with water is the only way to help prevent them from overheating, but those many tons of water, tainted with radioactivity, pose a separate threat.