Esso is being prosecuted after a dramatic incident in which part of Fawley refinery collapsed, allowing "dangerous" gas to escape.
The company allegedly failed to ensure that steelwork at the huge petro-chemical complex was kept in a good condition.
The resulting collapse, it is claimed, triggered the release of a dangerous substance known as liquid petroleum gas.
Esso is facing three charges in a prosecution brought by the Health and Safety Executive.
One of the allegations states that Esso failed to take all necessary measures to prevent major accidents and limit their consequences for human health and the environment.
According to the HSE, the company failed to ensure that a steel structure supporting E106 Fin Fans was inspected at suitable intervals. The subsequent collapse "resulted in a major emission of a dangerous substance".
The other two charges state that Esso failed to ensure the health and safety of its employees and people not in its employment.
The case, which relates to an incident on November 8 2022, is due to be heard at Southampton Magistrates' Court today.
As reported in the Daily Echo at the time, the incident caused widespread alarm among people living near the refinery.
The union Unite, which represents some of the 2,500 people employed at the site, said the drama involved a 100-tonne platform.
The GMB union also entered the debate, claiming the partial collapse of a cooling unit ruptured a pipe, causing a gas leak.
READ MORE: Fawley refinery: Unite says 100-tonne platform collapsed
In a statement issued shortly after the incident the refinery said: "Earlier this evening we experienced an operational issue on one of our units. Our own on-site teams are responding and working to address the situation and isolate the unit in question.
"We are using our flares, which are part of our standard safety and operational procedures, to assist with this work."
Unite's regional organiser, Malcolm Bonnett, emailed the refinery the next day and demanded an explanation.
Describing it as a major incident, he added: "Extremely lucky no one was killed."
READ MORE: Fawley refinery: Flares lit during 'operational incident'
An internal memo sent to Fawley staff on November 9 confirmed that a leak of liquid petroleum gas had taken place.
It added: "Our on-site response teams moved quickly to address this and safely isolated the unit. There were no injuries and the incident is fully under control."
Esso's parent company, ExxonMobil, added: "Safety is our top priority and we take any such incidents very seriously.
"We are investigating the incident and fully co-operating with the Health and Safety Executive.
"The cause of the incident has not yet been determined and it would be wrong and unhelpful to speculate until that work is complete."
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