More than 150 people participated in the protest camp outside the chemical plant Big flute Call for it to be closed.
They want factories to close and transition from fossil fuels to providing green jobs for affected workers.
The protests followed the community movement against burning at the plant, which recently reopened after a £140 million upgrade aimed at reducing burning.
Bryce Goodall, the activist of the local pressure group “Actions speak louder than words,” was one of those involved.
He said: “Mossmorran Operation Weekend is really incredible.
“We have united people in the local community, across Scotland and internationally, to support climate justice.
“This weekend, we have listened to the attention of the community and strengthened our athletic ability and skills, and are ready to further mobilize to achieve a just transition for Mossmorran and international workers and communities.”
Activist Mimblake of the Scottish Climate Camp said: “Protests and dissent are essential to democracy, challenge power and make the world a better place.
“After more than a year of lockdown, the climate crisis will only become more intense. This weekend is an opportunity to reorganize and prepare for a year’s climate action, because those in power seem unable or unwilling to do the right thing.”
The operator of the Fife Ethylene Plant (FEP), Exxon Mobil Exxon Mobil said in a statement: “Exxon Mobil believes that climate change risks are worth taking action, which will require all of us-businesses, governments and consumers-to make meaningful progress.
“Our focus includes reducing emissions, helping consumers reduce emissions, and developing low-emission energy solutions, including energy efficiency initiatives, biofuels, torch reduction, and carbon capture and storage (CCS).”
Their spokesperson stated that the company is “committed to making our operations quieter and less noticeable through a substantial investment in FEP,” including recent upgrades.
He added: “The Mossmorran facility is an integral part of Scotland’s energy supply and can meet the needs of communities across the country.
“In addition, FEP directly supports the manufacturing supply chain of important products such as medical supplies, electric vehicle parts and food packaging.”
