* BP suspends relief well drilling due to storm
* Storm on track to hit Louisiana coast on Thursday
* New Orleans judge to hear swath of BP civil cases (Adds tropical depression forming)
By Kristen Hays
HOUSTON, Aug 10 (Reuters) - An approaching storm in the Gulf of Mexico will delay by two to three days BP Plc's (BP.L) (BP.N) work on a relief well, the final step in permanently killing the source of the world's worst offshore oil spill, the top U.S. spill official said on Tuesday.
BP suspended work on the relief well aiming to bore into its blown-out Macondo well hours before the National Hurricane Center said a tropical depression formed over the Gulf of Mexico. [ID:nN10149983]
Computer models forecast the depression would move northwest, crossing the spill site before making landfall in Louisiana or elsewhere along the north-central Gulf coast by Wednesday night or early Thursday.
"This could potentially delay the final portion of the relief well for two to three days," retired Coast Guard Admiral Thad Allen told reporters earlier on Tuesday after the hurricane center said a tropical depression was likely.
Separately, a special judicial panel ruled that a New Orleans federal judge would oversee a swath of civil lawsuits brought by commercial fishermen and injured workers from the Deepwater Horizon rig, which exploded on April 20, killing 11 workers and unleashing a nearly three-month undersea oil gusher. [IDn:N10155602]
Securities lawsuits lobbed at BP by stockholders angered by its steep share price declines will be combined in Houston, the U.S. Judicial Panel on Multidistrict Litigation decided. The British energy giant has lost over a third of its market value since the explosion.
BP has reserved $32.2 billion to pay legal claims, but analysts said the eventual bill could run well above that.
The biggest U.S. environmental response operation passed a critical milestone last week by subduing the blown-out deepwater well with injections of heavy drilling mud, followed by a cement seal.
BP's Macondo well, a mile (1.6 km) down in the Gulf of Mexico, had been provisionally capped on July 15 after spewing an estimated 4.9 million barrels of oil into the Gulf, soiling marshlands, fisheries and tourist beaches along several hundreds of miles (kilometers) of the Gulf Coast.
The relief well is regarded as the final solution to plug the well 13,000 feet (4,000 metres) beneath the seabed. <^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ For full spill coverage link.reuters.com/hed87k Special report on new BP CEO Dudley [ID:nN29102489] Graphic on relief well link.reuters.com/xes52n Breakingviews [ID:nLDE6740LL] Political risk factbox on the U.S. [ID:nN02255831]
The storm could delay until the middle of next week the start of the planned "bottom kill" of the Macondo well, when the relief well is scheduled to intersect the well shaft, Allen said.
The actual kill operation still could take several days, officials say. The original schedule would have had the work starting by Sunday.
The enormous spill response operation is "moving into a new phase" to focus on shoreline cleanup and long-term recovery, Allen said. Crews are in the process of removing protective booms from the shores of Florida, Alabama and Mississippi, he said.
The government on Tuesday reopened 5,144 square miles (13,323 sq km) of Gulf waters to commercial and recreational fishing.
About 22 percent of federal waters in the Gulf are now closed, down from 37 percent at the height of the spill. (Additional reporting by Anna Driver in Houston, Martha Graybow in New York, Tom Hals in Wilmington, Delaware and Tom Brown in Miami; Writing by Chris Baltimore; Editing by Peter Cooney)