The drilling rig at the center of the Gulf of Mexico oil spill had a history of overdue maintenance tasks and a poor safety culture, the Sunday Times reported, citing an internal BP audit.
BP declined to comment on the report.
The paper said the review, carried out seven months before the Deepwater Horizon rig blew up in April killing 11 workers, identified 390 maintenance tasks that were overdue.
The auditors also said an annual health and safety plan was not in place and maintenance history was sub-standard, the paper reported.
Transocean said in a statement that all the tasks identified as critical were addressed immediately following the audit and the rig was found to be in good condition by a third party inspection just days before the disaster.
The Sunday Times also cited the auditors as saying the number of overdue tasks was excessive.
"The figure cited in the BP audit was artificially high because of a job duplication problem in the conversion of maintenance management software systems," Transocean said.