HOUSTON (Dow Jones)--The U.S. Government approved another 24-hour testing period for a cap that is keeping oil from spewing out of BP's PLC (BP, BP.LN) broken well, the federal response commander said Tuesday afternoon. Meanwhile, engineers and scientists are discussing the pros and cons of yet another way to stop the gusher, known as a "static kill," retired Coast Guard Adm. Thad Allen said in a conference call. In the so-called static kill operation, spill responders would inject drilling mud into the well. The procedure could enhance the company's ability to kill the well via a relief well, Allen said. The well, which once flowed at a rate of up to 60,000 barrels of oil a day, has been shut in since Thursday, when BP began testing a new containment cap. The cap was originally supposed to be tested for 48 hours, but Allen has granted four 24 hour extensions. Allen holds the power to call off the test of the cap at anytime. -By Susan Daker, Dow Jones Newswires; 713-547-9208; susan.daker@dowjones.com (END) Dow Jones Newswires July 20, 2010 16:32 ET (20:32 GMT)