BP was fined £400,000 yesterday for spilling almost four tonnes of crude oil in Shetland nearly seven years ago.
The energy giant admitted to falling short of its safety standards at Lerwick Sheriff Court.
The oil spilled onto the ground at Sullom Voe Terminal during maintenance work to drain a surge relief pipeline in December 2012, the UK Health and Safety Executive said.
BP said no one was injured and that there was “no impact on the environment”.
The firm no longer operates the terminal, which is now run by EnQuest.
HSE principal inspector Greg Haywood said: “This incident could so easily have been avoided by simply carrying out correct control measures and safe working practices.
“Companies should be aware that HSE will not hesitate to take appropriate enforcement action against those that fall below the required standards.”
A spokesman for BP said: “Our operations are underpinned by a relentless focus on safety and risk management. Regrettably, on this occasion in 2012, we fell short of these high standards.
“While there was no injury to people or impact on the environment, this incident should not have happened.
BP added: “We carried out a thorough investigation and applied lessons learned up until December 2017 when operatorship of Sullom Voe Terminal transferred to EnQuest.
“During that transition, we ensured all safety practices BP had built up at SVT over the years were transferred effectively to EnQuest.
“BP remains ever-committed to safe operations across our operations.”