MILLIONS of pounds of improvements at the Fife Ethylene Plant will cut the use of the elevated flare "by at least 98 per cent", according to the plant boss.

The burning of excess gas at the tall stack at Mossmorran has repeatedly led to the sky above being lit a fiery orange, visible for miles around, with complaints from local communities and politicians about the accompanying light pollution, noise and vibrations.

But manager Martin Burrell says ExxonMobil's investment at the chemical plant will mean this should become a thing of the past.

In an update to the community, he said: "Our further investment to introduce an enclosed ground flare, which will reduce the use of the elevated unit by at least 98 per cent, is progressing well and remains on schedule to be operational by the end of next year.

"We will continue to keep you and the wider community updated on its progress and the significant benefits it will bring."

ExxonMobil said their delayed £140m plant upgrade, which began in April and was completed last month, will help reduce the frequency of flaring.

It included a new noise and vibration-reducing elevated flare tip.

The plant was shut down while the work took place and the re-start began last week, with the company explaining beforehand that a day of elevated flaring would be necessary due to an increase in the volume of gas coming into the plant.

In an update on July 12, Mr Burrell said they had "safely returned to normal production and are no longer using our elevated flare".

He added: "We thank you and our communities for your patience while we completed our major upgrade project and plant re-start.

"We hope that the actions we took to minimise elevated flaring, as well as the benefits of the new flare tip, helped to reduce disruption to local communities.

"Our £140m plant upgrade saw us undertake over 21,000 individual work tasks, fit over 48,000 new parts and deliver more than 500,000 hours of skilled maintenance and upgrades.

"While we are confident the project will help to improve operational reliability and reduce unplanned flaring, FEP is a complex operation with our flare remaining a vital operational and safety system."

Flaring is the main cause for concern at Mossmorran and has seen the Scottish Environment Protection Agency (Sepa) give ExxonMobil, and neighbours Shell UK who run the Fife NGL Plant, final warnings in April 2018 after repeated episodes at their plants.

And last year the environment watchdog submitted a report to the Crown Office, seeking a prosecution for prolonged flaring at the FEP in April 2019, a week-long episode that led to more than 900 complaints, the most Sepa's pollution hotline has ever received.

There were a further 740 complaints after flaring last October and at that time First Minister Nicola Sturgeon pledged to consider an independent inquiry into Mossmorran.