The three companies involved in the Gulf of Mexico oil disaster lacked a safety culture and need a complete overhaul, a co-chair of the US presidential probe has said.
BP, Halliburton and Transocean are in need of top-to-bottom reform, according to William Reilly, co-chair of the presidential oil spill commission.
'We know a safety culture has to come from the top,' he added, as he opened the second day of a hearing into the 20 April explosion on a BP-leased platform off the Louisiana coast.
A seven-member panel has been tasked by US President Barack Obama with finding out the cause of the accident, which killed 11 rig workers and sparked the biggest maritime oil spill in US history.
Mr Reilly said the accident was caused by a 'culture of complacency' and a 'sweep of bad decisions' by the three companies, who were working together to drill a well more than a mile beneath the surface of the Gulf.
'If we had not been complacent, we would not have experienced two full months of a gushing well leading to 200 million gallons being spilled,' he said.
'There appeared to be a rush to completion of the Macondo well and one has to ask where the drive came from that made people determine they couldn't wait for sound cement or the right centralisers,' said Mr Reilly.
However, another investigator Fred Bartlit said he found no evidence BP and its partners had sacrificed safety for profits, putting him at odds with lawmakers.
Lawmakers have accused the oil companies of cutting corners to finish drilling the well, which was reportedly costing them $1.5m a day.
'To date, we have not seen a single instance where a human being made a conscious decision to favor dollars over safety,' Fred Bartlit, chief counsel to the commission, said.
Mr Bartlit said the initial assessment of the team that conducted the probe was that the explosion on the rig was caused by flammable hydrocarbons rushing up the casing of a riser pipe to the platform and exploding.
He also said the inquiry team agreed with 90% of the findings of BP's 183-page, in-house report released in September, but slapped the oil giant for taking 'unnecessary risks' that may have led to the platform explosion.
BP had repeatedly changed its plan for securing the well after drilling was completed.
It also took the unusual step of placing a cement plug to seal the well 900m below the surface instead of the usual 90m down, and then filling the space above it with water instead of heavier mud, the panel found.
'That cement plug acts as a backup barrier, just in case anything happens with the cement down at the bottom,' said Mr Bartlit.
'If hydrocarbons begin to leak in they will be stopped by that surface cement plug. We think BP introduced a certain amount of risk into the situation that we think may not have been necessary', he said.
Representative Edward Markey, also of the investigating committee, said the disaster was just the latest example of BP's 'long and sordid history of cutting costs and pushing the limits in search of higher profits.'
Commission co-chair Senator Bob Graham suggested all three companies involved made mistakes because of pressure to complete work on the well by 20 April.
'As a result of that, a number of things that might have made the outcome quite different were deferred or abandoned,' he said.
BP and Transocean workers on the rig failed to recognise warning signs on a computer, which were showing a dangerous build-up of hydrocarbons in the riser pipe just before the blast on the rig, the probe found.
