Engineers in Japan are battling to prevent a catastrophe at tsunami-hit Fukushima No. 1 nuclear power plant as anger grows over the handling of the crisis.
Workers at the plant were temporarily withdrawn after radiation levels spiked to their highest levels so far at Reactor 3 and a second fire broke out at Reactor 4, but they have now returned.
They were evacuated despite the authorities raising the maximum allowable exposure radiation dose for workers to 250 millisieverts from 100 millisieverts.
Japan’s chief cabinet secretary Yukio Edano said radiation levels outside the 18-mile exclusion zone were not high enough to cause an immediate health risk.
“People would not be in immediate danger if they went outside with these levels. I want people to understand this,” he told a news conference.
However, Mr Edano’s comments have failed to provide reassurance as thousands of people have been cleared from their homes, and thousands more have chosen to move away from the region surrounding the Fukushima plant.
The rapidly-changing situation has led France and Austria to urge its citizens to leave Tokyo and several large Nordic companies, including Ikea and H&M, offering to help their staff relocate further south.
Asian and European airlines also began diverting Tokyo flights to Osaka or cancelling them altogether.
In a rare live address, Japan’s Emperor Akihito thanked those involved in disaster relief across the country and expressed his deep concern about the escalating nuclear crisis.
Officials have been struggling to address the failure of safety systems at several of the plant’s reactors.
Of the six reactors at the plant, three were operating at the time of the magnitude 9.0 earthquake and tsunami.
Workers have requested an anti-riot water cannon from the Japanese National Police Agency to help pour water into a containment pool holding spent fuel rods.
High radiation levels had earlier prevented a military helicopter from dumping water onto worst-affected Reactor 3.
Tokyo Electric Power Co, which operates the Fukushima plant, has said that Reactor 3 is its top priority and shows the highest radiation levels at the site.
Reactor 4 is also causing concern after an explosion on Tuesday blew two holes in the wall of a building housing a pool of spent nuclear fuel, exposing it to the atmosphere.
“The situation at the No.4 reactor is not exactly a good situation but the No.3 reactor is a higher priority,” a company official told a media briefing.
The government has ordered some 140,000 people in the vicinity of the plant to stay indoors.
And those living less than 12 miles (20km) from the site have been told to evacuate.
A low level of radiation was also detected in Tokyo, triggering panic buying of food and water.
But the World Health Organisation has called for calm, saying there is no evidence of any significant spread of radiation.
The comments come after rumours circulated via text message claiming a radiation cloud threatened the whole of Asia.
“Governments and members of the public are encouraged to take steps to halt these rumours, which are harmful to public morale,” said Michael O’Leary, WHO’s representative in China.
“The situation is being monitored closely. More information would be shared promptly should the risk become more widespread.”
Meanwhile, the head of the UN nuclear watchdog is to travel to Japan on Thursday to assess what he called a “very serious” situation and urged the Japanese government to provide better information to his organisation.
US Congress said it was hoping to deploy equipment in Japan that can detect radiation exposure at the ground level.
The nuclear crisis has triggered international alarm and partly overshadowed the damage caused by the two natural disasters that killed an estimated 13,000 people.
It has also led to a worldwide review of nuclear technology.
