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

• A magnitude 6.5 earthquake shakes northern Japan, the latest in a series of aftershocks two weeks after the disaster.  Officials warn it will trigger a 50-cm (two-foot) tsunami wave.

• Workers were withdrawn from a reactor building at the quake-wrecked Fukushima Daiichi nuclear plant on Sunday after potentially lethal levels of radiation were detected in water there, a setback for the effort to avert a meltdown. Latest readings showed contamination 100,000 times normal in water at reactor no. 2 and 1,850 times normal in the nearby sea.

• Tokyo Electric Power Company (TEPCO), the plant's operator, acknowledges it faces a protracted and uncertain operation to contain overheating fuel rods and avert a meltdown.

• TEPCO earlier said it may have got the readings wrong and that it was conducting further checks. Experts say radiation in the Pacific will quickly dissipate and officials say levels away from the plant are not dangerous for humans.

• Workers had been trying to pump radioactive water out of the station. Three staff members were taken to hospital on Thursday owing to excessive radiation levels.

• Senior agency official says high levels of radiation in water accumulated in turbine buildings are probably caused by leakage from reactor vessels.

• Yukiya Amano, head of the U.N. nuclear watchdog, the International Atomic Energy Agency (IAEA), tells the New York Times the emergency "is a very serious accident by all standards" and could go on for weeks.

 • Japan's Nuclear and Industrial Safety Agency said at the weekend that storage of contaminated water must be handled carefully.

 • U.N. Secretary-General Ban Ki-Moon says it is time to reassess the emergency response framework of the international nuclear power industry. Leaders agreed at a European Union summit to submit reactors to "stress tests."

• Kyodo news agency, quoting a government source, says Prime Minister Naoto Kan's visit to the affected region the day after the disaster delayed TEPCO's response to the unfolding situation because of fears he could be exposed to radiation.

• Kan's approval ratings have edged higher, according to the first opinion poll taken since the quake and tsunami, with nearly two-thirds of respondents favoring a tax hike for reconstruction, a survey published by Kyodo news agency shows. But more than half disapprove of how the crisis involving the stricken nuclear plant has been handled.

• Kan said at the weekend that the situation at the plant was not getting worse, but is still nowhere near resolution.

• Japan chief cabinet secretary says 130,000 people living in an outer circle around Fukushima should consider leaving.

• Finance Minister Yoshihiko Noda says the government wants an extra post-quake budget by the end of April. Economics Minister Kaoru Yosano says the government may have to reconsider a plan to cut corporate tax rates.

• 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.

• 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.