Oil giant BP told a court hearing in New Orleans that oilfields services firm Halliburton destroyed damaging evidence relating to last year's oil well blast in the Gulf of Mexico.

The explosion aboard the Transocean-owned Deepwater Horizon, which was under charter to BP, killed 11 people and caused the largest oil spill in US history when the rig sank.

In the court hearing, BP accused Halliburton of "intentionally" destroying test results on its cement product used at the Macondo well and said the firm had failed to properly test its cement to see how it would perform under various conditions.

The cement used in the well is known to have been a key factor in the release of 780 million litres of crude oil into the Gulf of Mexico.

Halliburton says BP's claims are "without merit" and accused BP in a counter suit with the court of fraud and defamation.

The accusations comes as part of a legal battle in which BP and Halliburton are engaged ahead of a trial on damages scheduled for early next year.

Experts say the two firms are trying to attain the greatest legal advantage over the other ahead of the damages trial next year, which will apportion blame and quantify damages arising from the spill.

There will also be other phases of the case over clean-up costs and other claims.