China's flag carrier said on Tuesday it is cutting back on flights to Japan including Tokyo because of safety worries as the country battles the aftermath of a vast earthquake and tsunami.
But Air China said its worries related to aftershocks rather than to the nuclear crisis at a power plant in Fukushima, while other Asian airlines said they would continue flying to Japan as normal apart from tsunami-hit Sendai.
Despite rising concern in Japan over the atomic emergency, most countries in the region sought to dampen public fears, saying they did not think it necessary to screen passengers leaving Japan for radiation.
South Korea, however, said the measure was under discussion.
The nuclear crisis grew Tuesday as a two more blasts and a fire rocked the Fukushima No. 1 power plant and sent radiation to dangerous levels, with the prime minister's chief spokesman saying it was dangerous to human health.
In Tokyo, some 250 kilometres (155 miles) to the southwest, authorities said higher than normal radiation levels were detected, but not at harmful levels.
Countries including Australia and Thailand have already urged their nationals not to go near the stricken plant and to reconsider travel to other areas affected by Friday's 9.0-magnitude quake and the subsequent tsunami.
Air China cancelled half of its six daily Beijing-Tokyo flights for Tuesday and Wednesday, and one of its three Shanghai-Tokyo flights for each of the two days.
"We have cancelled some of the flights from China for safety reasons. But most flights remain normal," Air China spokeswoman Zhu Mei told AFP.
"The cancelled fights were those scheduled to stay one night at Japan airports. The planes could face danger in the event of aftershocks."
The airline's flights to Sendai were on hold after the airport there was reduced to wreckage by the tsunami that swept the country's northeast after the quake.
But Zhu said so far she knew of no new disruptions over radiation fears.
"We have not received a notice (on the radiation issue)," she said. Air China was not screening any incoming passengers for radiation.
Taiwan's EVA Airways has cancelled all flights to Sendai until June 30 and some flights to Tokyo and Sapporo for the rest of the month, but the country has not so far carried out radioactivity screening.
South Korean flights to Japan were operating as normal -- except to Sendai -- a spokesman for Incheon airport said, while Australian airlines Qantas and Jetstar said their flights were going ahead.
Indonesian and Hong Kong authorities and Singapore Airlines said their flight schedules would proceed, with Hong Kong saying passengers returning from Japan concerned about radiation exposure could visit a public hospital for a test.
Head of the International Atomic Energy Agency Yukiya Amano said Tuesday it was "very unlikely" Japan's problems could grow to resemble the nuclear crisis at Chernobyl in Ukraine, which caused widespread contamination in 1986.