A US judge has ordered urgent tests on the cement contractor Halliburton used to seal the BP oil well that blew out catastrophically in the Gulf of Mexico.
US District Judge Carl Barbier said some of the components may be "deteriorating over time" and that tests should be done "as soon as reasonably practicable".
The cement components had been subpoenaed by US government investigators looking into what caused the April 20 blow-out of the BP well being drilled by the Deepwater Horizon rig. Halliburton was hired to seal the well with cement.
The explosion aboard the Deepwater Horizon killed 11 workers and led to a spill of more than 170 million gallons of crude oil in the Gulf.
Halliburton's cementing work on the well has jumped to the forefront of investigations into the explosion. On Thursday, President Barack Obama's oil spill commission said tests performed before the blow-out should have raised doubts about the cement used to seal the well.
The cement mix's failure to prevent oil and gas from entering the well has been identified by BP and others as one of the causes of the accident.
Judge Barbier, who is overseeing lawsuits filed after the April 20 explosion, ordered tests on the same batch of cement used by drillers in the hours before the explosion.
Halliburton expected government investigators to retrieve the batch of cement components next week, said company spokeswoman Cathy Mann..
But Kenneth Arnold, a member of the National Academy of Engineering who served as an adviser to the US Department of Interior during its probes into the Deepwater Horizon explosion, questioned the importance of doing the tests on the cement components.
"The samples are old now," he said. "Whatever tests they do now are going to be open to interpretation." And he added that it would be hard to simulate the cement foam's properties in a laboratory and compare them with what happened inside the well.