He said pollution control department officials had expressed concern about the effects of the chemical used to clean up the spill.
PTTGC apologized for the incident and said the cleanup will likely be completed within three days.
“We acknowledge this incident has damaged our reputation and we will not let it happen again,” CEO Anon Sirisaengtaksin told a news conference.
In 2009, another PTT subsidiary was involved in the Montara oil spill, one of Australia’s worst oil disasters, in the Timor Sea off western Australia.