Radiation wafted from an earthquake-stricken nuclear power plant towards Tokyo on Tuesday, sparking panic in one of the world's biggest and most densely populated cities.

Women and children packed into the departure lounge at an  airport, supermarkets ran low on rice and other supplies and frightened residents, tourists and expatriates either stayed indoors or simply left the city.

'I'm not too worried about another earthquake. It's radiation that scares me,' said Masashi Yoshida, cradling his 5-month-old daughter Hana.

The nail-biting eased in the afternoon after Chief Cabinet Secretary Yukio Edano appeared on national television saying radiation levels at the troubled Fukushima Daiichi nuclear-power complex had fallen dramatically since morning.

But confidence in the government is shaken and many decided not to take chances, especially after radiation levels in Saitama, near Tokyo, were 40 times normal -- not enough to cause human damage but enough to stoke fears in the ultra-modern and hyper-efficient metropolis of 12 million people.

Many hoarded food and other supplies and stayed indoors. Don Quixote, a multistorey, 24-hour general store in Tokyo's Roppongi district, was sold out of radios, flashlights, candles, fuel cans and sleeping bags on Tuesday.

At another market near Tokyo's Yotsuya station, an entire aisle was nearly empty on both sides, its instant noodles, bread and pastry gone since Friday's earthquake and tsunami killed at least 10,000 people nationwide and plunged Japan into a twin nuclear and humanitarian crisis.

At Haneda Airport, hundreds of young mothers lined up with  children, boarding flights out of Tokyo.

'We are getting our of Tokyo and going to our home town because of the situation. For the time being we have bought a one way ticket and will wait and see what happens,' said a Japanese woman with an eight-month-old baby and four-year-old son, who declined to be identified by name.

Tourists such as Christy Niver, of Egan, Minnesota, said they had enough. Her 10-year-old daughter, Lucy, was more emphatic. 'I'm scared. I'm so scared I would rather be in the eye of a tornado,' she said. 'I want to leave.'

Winds over the troubled Fukushima Daiichi nuclear-power complex, about 240 km (150 miles) north of Tokyo, blew slowly southwesterly towards Tokyo for much of the day before shifting westerly later, a weather official said. Some scientists, however, urged Tokyo to stay calm.

'Radioactive material will reach Tokyo but it is not harmful to human bodies because it will be dissipated by the time it gets to Tokyo,' said Koji Yamazaki, professor at Hokkaido University graduate school of environmental science.

'If the wind gets stronger, it means the material flies faster but it will be even more dispersed in the air.'

University of Tokyo professor of bioengineering Hiroyuki Takahashi added: 'If the nuclear fuel remains contained, there will be very little health risk.'

Leaving Tokyo

The Czech Symphony Orchestra left Tokyo by bus for Ishikawa prefecture on the west coast.       'Some of them wanted to go home after the earthquake but it's pretty much impossible to get tickets for a hundred people now,' said Hitomi Sakuma, a friend of the orchestra who was seeing them off at a Tokyo hotel.

About 350 Japan-based expatriates at Infosys Technologies Ltd , India's second-largest software services exporter, are returning to India, its chief executive said.

'Some of them have returned, some are in the process of coming back,' S. Gopalakrishnan told Reuters. 'The revenue from Japan is very small and overall it will have a minimal impact on business.'

US banking giant Citigroup said it was keeping workers in Tokyo informed but there were no evacuation orders, said a spokesman, adding the bank was closely following guidance by the US Embassy, which has not urged nationals to leave.

Some international journalists covering the disaster from the worst-hit region around the northeastern city of Sendai, devastated by Friday's mammoth earthquake and tsunami that killed at least 10,000, were pulling out.

The Tokyo office of Michael Page International, a British recruitment agency, was closing for the week. 'I am leaving for Singapore tomorrow,' said one employee.

Levels of radiation had risen in Tokyo but for now were 'not a problem', the city government said.
Stranded airline passengers

Some Tokyo markets had run out of rice, a Japanese staple.

Yoshiyuki Sakuma, a musician who lives in Yashio city in Saitama prefecture, just north of Tokyo, searched for bread.

'If you lose electricity, water and gas, at least you can still eat bread,' he said.

The French Embassy advised citizens to leave. The German Embassy urged its nationals to consider doing the same, especially those with families.

Some wanted the government to expand the 30 km (18 km) evacuation zone surrounding the nuclear plant. 'The evacuation zone may not be enough,' said a Hiroshima-based Japanese scientist who treats nuclear radiation victims.

The number of stranded passengers at Tokyo's main international airport at Narita was rising but only China's national airline Air China  and Taiwan's EVA Airways cancelled flights to Tokyo.

Flights heading into Tokyo were nearly empty. 'I am afraid to go back,' Makoto Usui, 74-year-old air traveller as he was about to board a flight to Tokyo from Hong Kong. 'I don't know what to expect.'

The worst nuclear accident since the Chernobyl disaster in Ukraine in 1986 has drawn criticism that authorities were ill-prepared and revived debate about the safety of atomic power.

'Everything goes wrong. They say one thing and then do something completely different the next day,' Masako Kitajima, an office worker in her 50s, said of the administration's handling of the quake. – Reuters