International experts say Japan underestimated the threat posed by tsunamis to its nuclear power plants, but praised Tokyo's overall response to the massive earthquake and tidal waves that devastated the country's coastal northeast nearly three months ago.

The preliminary critique from the International Atomic Energy Agency was issued Wednesday by a team of 18 experts. It came after the team spent a week inspecting the crippled Fukushima-Daiichi power plant and the country's state of emergency preparedness ahead of the March 11 twin disasters.

The team's full report will be presented at an IAEA meeting beginning June 20 in Vienna.

Wednesday's report says Japanese officials did everything possible in the aftermath of the 9.0 earthquake and tsunami, which knocked out electric power and cooling systems and triggered partial core meltdowns at three of the plant's six reactors.

Experts called the government's response “exemplary.” But it also says the accident shows that nuclear plant designers in Japan and around the world must make greater efforts to anticipate and prepare for natural disasters.

The team also criticized Japan for failing to act on an IAEA recommendation three years ago that it separate its nuclear regulatory agency from its trade and industry ministry.

The IAEA team includes experts from France, Russia, China and the United States.

New evidence of radioactive leakage continues at the plant, almost three months after the accident. National broadcaster NHK reported Wednesday that high levels of dangerous strontium 90 have been found in soil samples around the plant.

Officials are also struggling to cope with rising levels of radioactive water in the basements of several of the reactors, fed by heavy recent rains.

The broadcaster also reported that a charity offering scholarships to children orphaned by the earthquake and tsunami has received applications on behalf of more than 1,100 children.