Japan's Emperor Akihito expressed his condolences Wednesday to victims of his country's massive earthquake and tsunami and told the Japanese people not to give up.

Speaking on TV Wednesday afternoon in a rare address to nation, he also voiced concern about the crisis at a nuclear power plant damaged by the disasters that has led to radiation leakage.

"I am deeply concerned about the nuclear situation because it is unpredictable," he said. "With the help of those involved I hope things will not get worse."

Friday's quake-spawned tsunami has devastated Japan's northeastern coast, and officials believe more than 10,000 people have died.

Akihito, 77, thanked those involved in disaster relief operations, including foreign governments, and urged an all-out rescue effort.

"We don't know the number of victims, but I pray that every single person can be saved," he said.

Japan faced a worsening nuclear crisis after authorities on Wednesday ordered emergency workers to withdraw from the Fukushima Dai-ichi nuclear power plant amid a surge in radiation, temporarily suspending efforts to cool the facility's overheating reactors.

Radiation levels fell later Wednesday, but it was not immediately clear if the workers had been allowed back in, or how far away they had withdrawn. The workers at the forefront of the fight _ a core team of 70 _ had been regularly rotated in and out of the danger zone to minimize their radiation exposure.

Meanwhile, officials in Ibaraki prefecture, just south of Fukushima, said radiation levels were about 300 times normal levels by late morning. While those levels are unhealthy for prolonged periods, they are far from fatal.