A controversial Fife chemical plant will be closed until at least November, BBC Scotland understands.
The Mossmorran plant, which has been at the centre of a number of flaring incidents, was temporarily shut down on 12 August.
ExxonMobil said it was extending the temporary closure so they could take time to make the plant more "reliable".
Mossmorran Action Group said shutdown meant there must have been a "catastrophic failure" at the plant.
Jacob McAlister, Exxonmobil's plant manager, estimated that operations would resume "at some point during the fourth quarter of the year".
He added: "This move gives us the extra time to thoroughly understand and address the mechanical issues with our boilers, while also undertaking a programme of wider preventative work that will further improve reliability when we re-start the plant.
"This temporary shut-down has a significant commercial and operational impact for our company, but it underlines our commitment to ensuring safe and reliable operations."
He said local people might see a small amount of steam from the plant's elevated flare stack over the coming days.
"This is from a temporary steam source we have installed simply to keep equipment warm as we progress our maintenance work," he added.
"Our team continues working 24/7 to complete this work, and we will continue to keep you informed on progress."
James Glen, chairman of the Mossmorran Action Group, said: "If Exxon is being shut down for so long, there has obviously been a catastrophic failure at the plant. Emergency shutdowns and major repairs should not be necessary if a plant is being maintained to the highest standards.
"After being promised the shutdown meant no more flaring, we've had Shell flaring almost continuously and now Exxon are announcing there will be further emissions from the elevated stack.
"As usual, Exxon is spinning a PR narrative which tells communities nothing reliable. Politicians and regulators such as the Health and Safety Executive who should be all over this are utterly ineffectual. Communities are sick to the back teeth."
Last week it emerged that environmental regulator Sepa has received almost 1,400 complaints about the Mossmorran site, which is shared by ExxonMobil Chemical Ltd and Shell Fife NGL.
Both companies had their permits varied and have been told to install flare tips that reduce noise.