BP has stopped the flow of oil and gas into the Gulf of Mexico from a ruptured oil well, US media reports say.
The company's "top kill" effort has plugged the leak and "stabilised the wellhead", Coast Guard commander Thad Allen was quoted as saying by AFP.
This is the first step, using mud, in BP's plan to seal the well for good with cement.
Eleven workers were killed in the initial explosion on the Deepwater Horizon rig five weeks ago.
Since then millions of gallons of oil have poured into the sea.
Adm Allen told US media the "top kill" procedure, which began on Wednesday, has pumped enough drilling fluid to block all oil and gas escaping from the well.
But he said there was still pressure from the well, although at very low levels.
Once engineers have reduced the pressure to zero, they will begin pumping cement into the hole to seal the well, he added.
This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.