NEW ORLEANS, Louisiana - The US government authorized BP to keep closed the busted Gulf of Mexico oil well for 24 more hours to allow tests Monday even though experts detected seepage from the surrounding seabed.
Admiral Thad Allen, the Obama administration's pointman on efforts to end the worst oil disaster in US history, made the decision after talks with federal scientists and BP to discuss a seep near the well and methane traces.
"I authorized BP to continue the integrity test for another 24 hours and I restated our firm position that this test will only continue if they continue to meet their obligations to rigorously monitor for any signs that this test could worsen the overall situation," Admiral Allen said in a statement.
The announcement last week that BP stopped the oil flow with a new cap, as it conducted key pressure tests on the well, had raised hopes of devastated coastal communities that their three-month nightmare may soon be over.
But fresh concerns were raised on Sunday after bubbles were detected at the site, even though BP said it did not believe they were caused by hydrocarbons -- meaning the wellbore reaching deep to the oil reservoir below may be compromised and leaking oil, even as it is choked off at the wellhead.
While Allen stopped short of ordering the immediate removal of the cap, which has halted the gusher of crude for the first time since April, he ordered BP to draw up an emergency plan for the possible reopening of the cap.
And in a letter on Sunday to BP's managing director, he said the British firm must inform the government within four hours of when seeps are detected, and raised concern over what he said was "lower than expected pressure readings."
"While we are pleased that no oil is currently being released into the Gulf of Mexico and want to take all appropriate action to keep it that way, it is important that all decisions are driven by the science," Allen told Bob Dudley.
"Ultimately, we must ensure no irreversible damage is done which could cause uncontrolled leakage from numerous points on the sea floor."
BP's chief operating officer Doug Suttles said pressure was rising slowly in the well as expected and touted "encouraging signs" that would allow the new cap to remain on until permanent relief wells can be drilled in August.
"In two different locations we've seen a few bubbles. This is not uncommon but clearly it's important that we check everything very closely so we're monitoring that," Suttles said.
BP has said the valves on the cap would remain shut as long as no leaks are discovered. The start of a two-week operation to plug the well permanently by pumping in heavy drilling fluids and then cement is now less than a fortnight away as engineers have only 100 feet (30 meters) left vertically to drill.
Gulf residents, who have seen the crude tarnish their shorelines and cripple the local economy since a rig leased by BP exploded and killed 11 workers in April, reacted cautiously to news that the cap was holding back oil.
"I don't know if it's going help. It's still a short-term fix," New Orleans resident and medical researcher Ashok Pullikuth told AFP. "The permanent fix is the relief wells. This cap has saved a month's worth of spill damage."
Measuring devices on BP's latest cap have given steadily increasing high-pressure readings since tests began Thursday on the well bore, which stretches 2.5 miles (four kilometers) below the seabed.
Seismic and sonar surveys and video footage filmed by robotic submarines in the murky depths of the Gulf have been monitoring whether any oil or gas was leaking through the rock formations on the sea floor.
Allen did not specify what sort of "seepage" or "anomalies" the testing had found but warned earlier that "ultimately, we must insure no irreversible damage is done which could cause uncontrolled leakage from numerous points on the sea floor."
BP said in a statement Monday that the current 3.95-billion-euro total cost of its response to the spill so far included 67,500 compensation payouts totalling 207 million dollars.
The total includes the bill for containing and cleaning spilt crude, relief well drilling, grants to Gulf states and money paid to the US federal government, it said in a statement.