People living around Mossmorran reported the petrochemical plant for generating ‘extreme’ noise on Friday night.
Scotland’s environment watchdog Sepa said it had received numerous complaints against operator ExxonMobil Chemical.
Residents in nearby Cowdenbeath and Lochgelly compared the rumbling to a jet engine and said sleep had been disturbed.
Sepa said it was told the sound was from routine decoking activity at Fife Ethylene Plant and that efforts were being made to reduce it.
Mossmorran Action Group chairman James Glen said: “We started getting complaints about extreme noise from residents last night.
“When one resident contacted Exxon, he got an outright denial that there was any noise at all.
“People in Lochgelly and Cowdenbeath suffered an anxious, sleepless night because the plant was so loud.
“Exxon need to come clean about what they are doing.”
— Scottish Environment Protection Agency (@ScottishEPA) May 29, 2020
A Sepa spokeswoman said: “Following a number of reports of noise at ExxonMobil, Mossmorran, late on Friday night officers contacted the site and were informed that steps were being taken to reduce noise.
“Officers were in contact with the site again on Saturday and understood that the routine decoking activity, believed to be the cause, was expected to conclude on Saturday.
“Sepa noise monitoring remains in place.”
ExxonMobil Chemical was contacted for comment.
The operator could face prosecution over an unscheduled flaring episode in April last year.
Just over a fortnight ago Sepa announced it was submitting a report to the Crown Office and Procurator Fiscal Service, following a lengthy investigation.