The three-member International Atomic Energy Agency (IAEA) team was at the uranium processing plant where three plant workers set off a self-sustaining nuclear reaction.

The leak at the site run by JCO Co Ltd in Tokaimura, 120 kilometres northeast of Tokyo, exposed 49 people to radiation and forced more than 320,000 to shelter at home for more than a day.

The IAEA team arrived here on Wednesday on a five-day visit. "Since they came here all the way from Vienna I expect they will examine the site as much as possible," said a JCO official.

Another company official said the IAEA experts were speaking to JCO managers but they had no plans to enter the radioactive building itself, which is sealed off.

The IAEA offered to send a team immediately after the accident but was turned down by Japanese authorities who laterexplained the situation had been too dangerous and hectic.

Three JCO workers, two now critically ill, illegally used steel buckets to pour 16 kilograms of uranium into settling tanks, triggering a self-sustaining nuclear reaction.

The Japanese government said three US nuclear experts would also visit Tokaimura next week to inspect the accident site. "The US side offered the despatch of experts to understand what happened in the accident, and we accepted its offer in the context of increasing transparency and securing confidence from the international community," the Science and Technology Agency said in a statement.

The US team was scheduled to visit Japan from October 18 to 19.