The Ministry of Natural Resources and Environment has criticised Star Petroleum Refining Public Company Limited (SPRC) for ignoring a command to halt work and causing a second leakage of crude oil in Rayong province within two weeks of the first spill on Jan 25.
The ministry urged the police on Friday to launch an investigation into the company over its pipeline operations, as it had been told to cease operations in the wake of last month's incident.
Earlier on Thursday, SPRC revealed that at least another 5,000 litres of crude oil had leaked from the same underwater pipeline off the coast of Rayong.
Environment Minister Varawut Silpa-archa said the company failed to give clear or adequate answers to key questions when grilled on the matter by a panel, including the exact size of the oil spill and why the company broke an order to suspend the pipeline's operation.
"We have no authority to investigate the case so we would like the police to help us clarify the facts. We are wondering why the company restarted the pipeline operation despite the authority's order to suspend it," Mr Varawut said.
"I should not say this mistake was caused by the company's ignorance and carelessness. But if it wants to do business in Thailand, it must follow the regulations."
The Department of Pollution Control is now considering the company's request to use an additional 5,000 litres of dispersant chemicals to clean up the spill, according to department chief Attaporn Charoenchansa.
Over 83,000 litres of such chemicals have already been used to control the first spill.
The department said it found high levels of heavy metal and hydrocarbon in the affected seas, exceeding the safety standard.
Phuriphat Thirakunphisut, deputy director-general of the Marine Department, said the firm has been told to commence tier-1 emergency operations, set up oil booms and provide boats to support the department.
The oil sludge has been contained but surveillance will be beefed up for closer monitoring, Mr Phuriphat added.
The Rayong branch of the Marine Office has been instructed to engage a third party, such as the Council of Engineers Thailand, to inspect for the area for safety.
The damage will then be restored, and an Environmental Impact Assessment (EIA) study conducted.