A prosecution is being called for into the release of hydrocarbons at Mossmorran chemical works in Fife.
The UK’s Health and Safety Executive has formally submitted a report to the Crown Office.
It follows findings uncovered by inspectors during a routine inspection in spring 2019.
An HSE investigation report into ExxonMobil’s Mossmorran site was formally submitted to COPFS last month.
The investigation specifically relates to hydrocarbon releases, which were uncovered by inspectors during a routine inspection in Spring 2019.
Principal Inspector of Health and Safety Greg Haywood said: “Thorough enquiries have been made into this issue and a formal report has been submitted to the Crown Office & Procurator Fiscal Service.
“We are unable to comment further at this time.”
ExxonMobil, the Fife Ethylene Plant owner, said it had now resolved the issue of the hydrocarbon releases.
Last year environmental watchdog Sepa sought prosecution following flaring in April 2019 for six days, which led to more than 900 complaints.
ExxonMobil has since committed to spending £140m on improvements.
Mossmorran Action Group said they had previously raised the issue of leaky pipework at the site, as well as emissions from the main chimneys.
They were concerned that while steam could be seen rising from the pipes, invisible gases could also be escaping at the same time.
An ExxonMobil spokesman said: “We were fully aware of, and were actively working solutions to, these matters.
“We cooperated constructively with the HSE, and these matters have since been resolved.
“Fife Ethylene Plant works within the highest regulatory standards, is committed to its environmental responsibilities and complies with all applicable laws.
”We operate to the very highest safety and risk management practices, and work closely with the HSE in full compliance with their approved processes.”