As of now, the oil has stopped:
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.
“They’ve been able to stabilise the wellhead, they’re pumping mud down it. They’ve stopped the hydrocarbons from coming up,” Adm Allen told WWL First News radio.
It was the first positive official assessment of BP’s latest attempt to plug the well, after previous efforts failed.
BP has not yet commented in detail on the situation, saying merely that the operation was continuing.
Adm Allen 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.
You can watch a live feed of the top kill op here.