(For story on spill anniversary, click [ID:nN14225897])
April 15 (Reuters) - Last year's Deepwater Horizon rig accident in the Gulf of Mexico killed 11 workers and unleashed the worst offshore oil spill in U.S. history.
Here is a timeline of the accident and spill saga:
April 20, 2010 - Explosion and fire on the Deepwater Horizon drilling rig kills 11 workers. The rig, owned by Transocean Ltd and licensed to BP <BP.L> <BP.N>, was drilling 42 miles (68 km) southeast of Venice, Louisiana, in 5,000 feet (1,525 metres) of water. The well had reached 13,000 feet (4,000 metres) under the seabed.
April 22 - The rig, valued at more than ${esc.dollar}560 million, sinks and a 5-mile (8-km) oil slick forms.
April 30 - BP CEO Tony Hayward says the company takes full responsibility and will pay all legitimate claims and the cost of the cleanup. Analysts say containment and cleanup costs could top ${esc.dollar}3 billion.
May 10 - BP says it has spent ${esc.dollar}350 million dealing with the leak. Analysts at Exane say BP may have to take a ${esc.dollar}10 billion provision for the incident. Other analysts estimate the total cost between ${esc.dollar}5.1 billion and ${esc.dollar}8.2 billion.
May 11/12 - Executives from BP, Transocean <RIG.N> <RIGN.VX> and Halliburton <HAL.N> appear at congressional hearings in Washington. The executives blame each other's companies.
June 9 - U.S. Interior Secretary Ken Salazar says BP must pay the salaries of thousands of workers laid off because of the moratorium on deep-sea drilling.
June 16 - Hayward and BP Chairman Carl-Henric Svanberg meet White House officials and announce a deal to set up a ${esc.dollar}20 billion fund for damage claims from the spill. BP also suspends dividend payments to shareholders; says it will pay ${esc.dollar}100 million to workers idled by the six-month drilling moratorium.
June 22 - Under fire, Hayward hands day-to-day control of spill operations to managing director Bob Dudley, who had been CEO of BP's Russian joint venture, TNK-BP.
June 25 - BP says it has spent ${esc.dollar}2.35 billion on the response effort, including ${esc.dollar}126 million in claims to those affected by the disaster.
July 19 - BP says it has spent ${esc.dollar}3.95 billion so far on efforts to tackle its well.
July 20 - BP says it has reached a deal to sell ${esc.dollar}7 billion in assets to Apache Corp <APA.N> as it raises money to cover costs related to the spill. It later says it plans to sell assets worth up to ${esc.dollar}30 billion over 18 months.
July 27 - BP names Dudley as its next CEO.
Aug. 2 - U.S. government data shows 4.9 million barrels of oil leaked before the well was capped.
Sept. 16 - Relief well intercepts the Macondo well.
Sept. 19 - With a final shot of cement, BP permanently "kills" the leaking well.
Sept. 23 - Researchers put the spill at around 4.4 million barrels. The figure comes from the first independent study of the disaster.
Sept. 26 - Halliburton, the oilfield services company that cemented the blown-out well, says a BP report laying the blame on the cement job offers a questionable account of events and "erroneous conclusions."
Oct. 4 - BP says it is to raise 2 billion euros (${esc.dollar}2.7 billion) via a bond issue to help finance its ${esc.dollar}20 billion compensation fund.
Nov. 2 - BP increases its estimate of the likely cost of the spill to ${esc.dollar}40 billion from ${esc.dollar}32 billion.
Nov. 9 - Shares in BP rise after a U.S. presidential panel says it found no evidence that BP deliberately chose to cut corners to save costs.
Dec. 15 - The Obama administration launches a legal battle against BP and its partners by suing them for the oil spill, which could cost the companies billions of dollars.
-- The lawsuit seeks damages from the well owners BP, Anadarko Petroleum Corp <APC.N> and Mitsui & Co Ltd unit MOEX, and well driller Transocean and its insurer QBE Underwriting/Lloyd's Syndicate 1036, part of Lloyds of London, for their roles in the disaster.
Jan. 5 - BP and its partners made a series of cost-cutting decisions that ultimately contributed to an oil spill, the White House oil spill commission says in a report on the causes of the largest offshore oil spill in U.S. history.
-- The commission says BP and its collaborators lacked a system to ensure their actions were safe.
Jan. 11 - The White House oil spill commission, in its final report of the BP drilling disaster, says the U.S. government needs to expand its drilling regulations, as well as set up an independent drilling safety agency, because the regulatory system was unprepared for the disaster.
-- Most of the recommendations require approval from the U.S. Congress, which will be difficult as Republican lawmakers fear extensive new regulations would slow oil drilling. Oil companies expressed similar concerns, saying hampering offshore production with burdensome rules would drive up oil prices. (Writing by David Cutler, London Editorial Reference Unit; Editing by Pascal Fletcher and Philip Barbara);
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