BP claims "milestone" as drill mud holds well shut

"The MC252 well appears to have reached a static condition -- a significant milestone," BP said in a statement, adding that the deepwater well's pressure was now being controlled by the heavy drilling mud pumped in on Tuesday.

The next step in the process, called "static kill", is to pump in cement behind the mud as a seal, but BP said further monitoring was required to see if more mud should be pumped in first.