The United Nations nuclear agency says there have been positive developments in Japan's efforts to tackle a nuclear emergency after the 11 March quake.

联合国原子能机构称，日本在对待3·11大地震所引发的核泄漏所做的救援工作是富有成效的。

The IAEA said smoke or vapour（蒸气） rising from one of the overheating reactors¹ at the damaged Fukushima power plant had become less intense.

But it said the overall situation remained very serious.

The overall death toll² after the earthquake has now risen to 8,450, with 12,931 people missing.

Electricity has been restored to three reactors at the crippled（残废的） Fukushima nuclear power plant - this should allow the use of on-site water pumps soon.

Engineers have been spraying fuel rods with salt water to try to them the rods cool enough to avert³ radiation leakage⁴.

Villagers living near the plant have been told not to drink tap water due to higher levels of radioactive iodine⁵（碘） .

"There have been some positive developments in the last 24 hours but overall the situation remains⁶ very serious," said Graham Andrew, a senior official of the International atomic Energy Agency.

"We consider that now we have come to a situation where we are very close to getting the situation under control," Deputy Cabinet Secretary Tetsuro Fukuyama said.

However, bad weather forced the Japanese Prime Minister, Naoto Kan, to cancel a planned visit to emergency workers near the Fukushima plant.

It is also making the recovery work a much more grim and difficult task.

Search-and-relief efforts in the prefecture of Miyagi, where the police chief believes the final quake-tsunami death toll could reach 15,000, have been delayed by driving rain.

"We basically cannot operate helicopters in the rain," Miyagi official Kiyohiro Tokairin said.

"We have been using helicopters to deliver relief goods to some places but for today we have to switch the delivery to places that we can reach by road," he said.