Signs of rising radiation levels on Thursday indicated Japanese authorities were far from bringing the tsunami-stricken Fukushima reactors under control.
Taiwan and South Korea both reported detecting radiation on the clothes of travellers arriving from Japan. Helicopter-borne loads of water were dropped on two of the reactors but initial reports indicated no drop in radiation.
Other countries announced further plans to bring in more and larger airplanes to evacuate their citizens. Officials said about a fifth of the 25,000-strong Indian community had left Japan.
However, many foreigners refused to leave. Infosys, for example, said it would not close its office. Foreign governments also rushed in emergency supplies. France sent 100 tonnes of boric acid, a chemical used to dampen radiation. A flotilla of 14 US warships provided floating platforms for Japanese aid workers and was being used to send large water pumps.
There was panic buying in nearby states like China and Russia of iodine tablets, seaweed and red wine - substances believe to help against radiation poisoning.
Four Chinook helicopters were used to dump seven tonnes of water on reactors No. 3 and 4. The main target seems to have been to replenish reservoirs holding spent nuclear fuel rods. These rods, which have no containment vessel, are seen as the most likely source of a major radiation leak. Japan disputed claims by US officials that the reservoirs in two reactors were now dry - which would mean rapidly heating rods and eventually a radiation leak.
Japan said it would continue with airborne water drops, though initial results indicated radiation levels were continuing to rise. Two military fire trucks joined efforts to spray the reactors with water to keep temperatures under control. Crews also laid a new power cable to the reactors. Power failure was the reason the reactors' cooling systems had shut down.
The count of dead and missing from the earthquake-tsunami that hit Japan a week ago passed 15,000.
Many foreigners indicated they were leaving as much because of the bitter cold weather, which is hampering relief efforts, and continuing nationwide power cuts as a fear of radiation.