Washington, May 27 (DPA) Oil giant BP’s top-kill operation was proceeding as expected Thursday and may have already succeeded in temporarily plugging the leak at a ruptured oil well at the bottom of the Gulf of Mexico.

US Coast Guard Admiral Thad Allen said in an interview with the Los Angeles Times that BP had managed to stop the leak. Engineers had forced enough heavy mud into the damaged well head to reduce the upward pressure and prevent oil and gas from gushing out.

A Coast Guard spokeswoman later clarified that Allen ‘did not declare success.’ The top-kill procedure would temporarily stop the leak ‘simply because of the pressure from the mud injection.’ That did not necessarily mean the operation had worked, though ‘things were going according to plan,’ spokeswoman Lisa Novak said.

The top-kill operation launched at 1 p.m. (1800 GMT) Wednesday marks the first time that BP has tried to permanently seal off the well since the April 20 explosion of the Deepwater Horizon oil rig. Past efforts have focussed on siphoning off the spewing oil.

BP has sounded a more cautious noted. Managing Director Bob Dudley told broadcaster CNN Thursday morning that the ‘operation is proceeding like we expected.’ A full update was expected in the afternoon.

Meanwhile, the US government said that the amount of oil that has been flowing into the Gulf is much more than originally estimated.

The government now believed anywhere from 12,000 to 25,000 barrels of oil per day were spewing out of the well, up dramatically from the initial prediction of just 5,000 barrels per day.

Marcia McNutt, director of the US Geological Survey said the estimates were still preliminary. Predicting the flow rate was still a ‘highly dynamic, complex situation’.

A total of 270,000 barrels of oil per day has come up to the surface since the April 20 explosion, McNutt said.