Contractors who worked for BP on the ill-fated Deepwater Horizon oil rig have criticised the company’s report into the Gulf of Mexico oil spill.

Drilling firm Transocean branded the report “self serving” while cement contractor Halliburton said it contained “omissions and inaccuracies”.

BP blamed a “sequence of failures involving a number of different parties” for the spill.

It faces billions of dollars worth of compensation claims over the disaster.

Transocean dismissed BP’s report, accusing the oil giant of having designed a “fatally flawed” well and making “cost-saving decisions that increased risk – in some cases, severely”.

“This is a self-serving report that attempts to conceal the critical factor that set the stage for the Macondo (well) incident: BP’s fatally flawed well design,” the Swiss-based group said in a statement.

Halliburton also hit back at the 193-page report.

“As we continue to review BP’s internal report published earlier today, we have noticed a number of substantial omissions and inaccuracies in the document,” it said.

“Halliburton remains confident that all the work it performed with respect to the Macondo well was completed in accordance with BP’s specifications for its well construction plan and instructions, and that it is fully indemnified under its contract for any of the allegations contained in the report.”