BP said in a statement that its third quarter results, normally reported on the last Tuesday of the month after the end of a calendar quarter, would now be released on 2 November, rather than 26 October.
A spokesman said the decision followed the company finding the preparation of its previous quarterly results challenging to complete within the normal timeline, and denied it was related to the discovery of any new liabilities.
On Wednesday, BP produced an internal investigation into the explosion on the Deepwater Horizon drilling rig, which exploded on 20 April, and sunk, leading to the United States' worst ever oil spill.
The spokesman said the team compiling the report, which laid most of the blame on the companies BP hired to drill the well, had been supported by internal and external lawyers.
However, he said the lawyers had been "ring-fenced" from the rest of BP and denied their role was to frame the report – much criticised by the contractors and US politicians – so as to help BP fend off lawsuits.
"Their role was to make sure everything in the report was legally watertight," spokesman Andrew Gowers said.