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.

• UN watchdog suggests widening of the exclusion zone around Fukushima nuclear power station after radiation measured at a village 40 km from the facility exceeds a criterion for evacuation.

• Japan's nuclear safety agency said extending the zone should be considered, but Chief Cabinet Secretary Yukio Edano gave no indication the government was poised to do it.

• The consistently high levels of radiation found in the sea outside the plant complex may mean that radiation is leaking out continuously, Japan's nuclear watchdog said on Thursday.

• The level of radioactive iodine found in seawater near the  stricken nuclear power plant was 4,385 times more than the legal limit on Thursday, the nuclear safety agency said. That was the highest recorded since the crisis began.

• Japan's government may need to spend over 10 trillion yen ($120 billion) in emergency budgets for disaster relief and reconstruction, the country's deputy finance minister, Mitsuru Sakurai, signaled on Thursday.

• Japanese manufacturing activity slumped to a two-year low in March and posted the sharpest monthly fall on record as the quake and tsunami hit supply chains and output.

• French President Nicolas Sarkozy, who chairs the G20 and G8 blocs of nations, due to arrive in Tokyo on Thursday. He will be the first foreign leader in Japan since the March 11 quake and tsunami. France also flew in two experts from state-owned nuclear reactor maker Areva and its nuclear research body to assist Japan's heavily criticized plant operator Tokyo Electric Power Co (TEPCO).

• Singapore has told the U.N. nuclear watchdog some cabbages imported from Japan had radiation levels up to nine times the levels recommended for international trade. Japan urges the world not to impose "unjustifiable" import curbs on its goods.

• Japan says comprehensive rules will be drawn up for power plant operators in light of the accident that ripped apart the Fukushima Daiichi nuclear power station. It was the first acknowledgment that norms were insufficient when the March 11 earthquake and tsunami wrecked the facility.

• Plant operator TEPCO says its chairman is at the firm's helm after its president, barely seen since the crisis began, was taken to hospital suffering from high blood pressure and extreme dizziness. Chairman Tsunehisa Katsumata says TEPCO wants to remain a publicly listed company while acknowledging that emergency loans of 2 trillion yen ($24 billion) will not cover current costs.

• Around 27,500 people dead or missing from the earthquake and tsunami. About 173,600 living in shelters on high ground above the vast plains of mud-covered debris.

• 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 in 2005 caused $81 billion in damage.