BP Plc got the green light late Wednesday to inject cement down the pipe into its damaged well - the next step in sealing off the Gulf of Mexico oil gusher.
National incident commander Thad Allen, the retired US Coast Guard admiral overseeing the clean-up and containment of the three-month-old disaster, said he had authorised BP to "cement its damaged well".
The decision was made based on the successful completion of a heavy mud injection - called static kill - earlier in the day.
But Allen emphasized that BP must still complete the parallel relief well that will be used to pump another dose of cement into the bottom of the well 5 kilometres below the floor of the Gulf.
"I made it clear that implementation of this procedure shall in no way delay the completion of the relief well," Allen said in a statement.