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.

• Japan warns it could take months to stop radiation leaking from the nuclear plant.

• Engineers mixed sawdust and newspapers with polymers and cement to try to seal a crack in a concrete pit at the Fukushima Daiichi complex's reactor no.2, where radioactive water has been seeping into the sea. Operator Tokyo Electric Power Co (TEPCO) said over the weekend it found the crack, which was generating readings of 1,000 millisieverts of radiation per hour in the air inside.

• The majority of voters polled by a newspaper say a coalition would better handle the crisis and post-quake recovery effort.

• An aide to embattled Prime Minister Naoto Kan says the government's priority is to stop radiation leaks which were scaring the public and hindering work on cooling overheated nuclear fuel rods. He says the situation had "somewhat stabilized."

• A central bank survey, underlining the concern over the impact of the crisis, shows that big manufacturers expect business conditions to worsen significantly in the next three months, though they were not quite as pessimistic as some analysts had expected.

• Engineers examine alternatives to pumping in water to cool the reactor, including an improvised air conditioning system, spraying fuel rods with vaporized water or using the plant's cleaning system.

• Radiation levels in the sea nearby stand at 4,000 times the legal limit.

• TEPCO has said it will scrap at least four reactors once they are under control, but this could take years or even decades.

• A U.N. watchdog has suggested widening of the exclusion zone around the station after radiation measured at a village 40 km distant exceeded a criterion for evacuation.

• 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.

• A total of 12,087 people were confirmed dead by Japan's National Police Agency, while 15,552 are missing. A total of 167,700 households were without electricity and at least 200,000 without running water.

• Estimated cost of damage 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.