METAIRE, La. – Coast Guard Adm. Thad Allen says BP has successfully sliced off a pipe in an effort to contain the Gulf oil, but the cut is irregular and placing a cap over the spill will be more challenging.

Allen said Thursday that the cap was over the gusher and expected to be lowered in the next couple of hours.

This is BP's latest attempt to contain the oil. The best chance to plug the leak is still two months away.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

PENSACOLA, Fla. (AP) — BP's top executive acknowledged Thursday the global oil giant was unprepared to fight a catastrophic deepwater oil spill as engineers were forced yet again to reconfigure plans for executing their latest gambit to control the Gulf of Mexico gusher.

BP PLC planned to use giant shears to cut a pipe a mile below the sea after a diamond-tipped saw became stuck halfway through the job, another frustrating delay in six weeks of failed efforts to stop or at least curtail the worst oil spill in U.S. history. The government's point man for the disaster, Coast Guard Adm. Thad Allen, said on the NBC "Today" show the cut would be made later Thursday.

Once the riser pipe is cut, BP hopes to cap it and start pumping some crude to a surface tanker, which would reduce but not end the spill. The next chance for stopping the flow won't come until two relief wells meant to plug the reservoir for good are finished in August, after an effort to staunch the gusher with heavy mud failed Saturday.

BP Chief Executive Tony Hayward told The Financial Times it was "an entirely fair criticism" to say the company had not been fully prepared for a deepwater oil leak. Hayward called it "low-probability, high-impact" accident.

"What is undoubtedly true is that we did not have the tools you would want in your tool-kit," Hayward said in an interview published in Thursday's edition of the London-based newspaper.