HOUSTON, Sept. 19 (Xinhua) -- British oil giant BP had permanently "killed" the leaking Macondo well in the Gulf of Mexico, the U.S. spill commander said on Sunday.

Retired Coast Guard Adm. Thad Allen, who is tasked to oversee the spill response, said on Sunday the months-long underwater gusher "is effectively dead" and "poses no continuing threat to the Gulf of Mexico."

A pressure and weight test to ensure that a cement plug would hold was completed at 5:54 a.m. CDT, according to Allen.

BP finished pumping cement into the damaged Macondo well on Friday and had been waiting for the results of the test before officially declaring the well is plugged for good.