BP's cement contractor on the drilling rig that exploded, causing the worst offshore oil spill in US history, said its recent discovery of missing cement samples was the result of a "simple misunderstanding", not an attempt to withhold crucial evidence.
In a New Orleans court filing, Halliburton lawyers accused BP of trying to create a "sideshow" during an ongoing trial over the deadly 2010 disaster in the Gulf of Mexico which led to the deaths of 11 rig workers.
They said the British oil giant was trying to deflect attention from its own actions.
"There is no evidence that (Halliburton) acted deliberately or intentionally, or that the isolation of the (missing cement) was the result of anything other than a simple misunderstanding," Halliburton lawyers wrote.
Last week, BP asked US District Judge Carl Barbier to sanction Halliburton for allegedly destroying evidence that could have been used at trial. BP cited the allegations as grounds for the judge to rule that Halliburton's cement design on the drilling project was unstable before the April 2010 blowout of BP's Macondo well.
Halliburton lawyers dismissed BP's request as "the latest chapter in its book of finger pointing".
Earlier, the judge, who is hearing evidence without a jury, told lawyers he was not certain how soon he would rule on the issue. Barring a settlement, he could decide after the trial how much more money BP and its contractors owe for their roles in the catastrophe.
Earlier this month Halliburton discovered cement samples at a laboratory that were not turned over to the US Justice Department for testing after the spill.
Tim Quirk, who was a Halliburton laboratory manager, said he secured all of the samples he believed were related to the Macondo well in a locker and stored others in a warehouse, never suspecting the recently-discovered samples could be related to the case.
"I had no way of knowing," he said.