Following are main developments after a massive earthquake and tsunami devastated northeast Japan and crippled a nuclear power station, raising the risk of an uncontrolled radiation leak.

• Plutonium found in soil in five places at the Fukushima plant heightening alarm over a protracted battle to regain control of facility. Plant operator Tokyo Electric Company (TEPCO) says traces of plutonium found were of level not harmful to human health.

• Japan's Nuclear Industrial Safety Agency said the plutonium discovery could mean the reactor's containment mechanism had been breached.

• Nuclear safety agency says amount of plutonium detected near the plant is similar to that which would result from a nuclear test, but is not harmful to humans.

• Some opposition lawmakers criticized Prime Minister Naoto Kan on Tuesday for not widening the exclusion zone around the plant.

• PM Kan says the situation at the nuclear power station required utmost vigilance. Workers resigned to a struggle of weeks or even months to re-start cooling systems vital to control the reactors and avert disaster.

• National Strategy Minister Koichiro Gemba says nationalization of TEPCO, Asia's largest utility, is one option being considered.

• French President Nicolas Sarkozy will visit Japan on Thursday to meet Prime Minister Naoto Kan, Kyodo news agency reports, and he will become the first foreign leader to visit since the earthquake and tsunami.

• France is also sending a team of nuclear experts from Areva and its CEA nuclear research body at the request of Japanese authorities.
• Environmental group Greenpeace says it has detected high levels of radiation outside the 20-km (12-mile) exclusion zone, but Japanese officials say levels away from the plant are not dangerous for humans.

• TEPCO is seeking help from French firms including Electricite de France and Areva  to stabilize reactors at the Fukushima complex, some 240 km (150 miles) from Tokyo, Kyodo news agency reports.

• Experts say radiation in the Pacific will quickly dissipate and officials say levels away from the plant are not dangerous for humans.

• Official death toll from earthquake and tsunami exceeds 10,804, according to national police. Total number of missing stands at 16,244. Nearly a quarter of a million people are living in shelters.

• Estimated cost of damage from the earthquake and tsunami to top $300 billion, making it the world's costliest natural disaster. The 1995 Kobe quake cost $100 billion while Hurricane Katrina caused $81 billion in damage.