Assurances have been issued by an environmental agency after “intense flaring” at a chemical plant in Fife sparked alarm.

The “flames” from ExxonMobil’s Mossmorran plant near Cowdenbeath could be seen for miles on Thursday night, with many taking to social media to express fears.

One Twitter user in Edinburgh described the flare “as bright as streetlights” despite being 12 miles away.

READ MORE: Investigation launched into unplanned flaring at Mossmorran power plant

Several others went further, suggesting the bright flare reminded them of Mordor's Mount Doom from the Lord of the Rings series.

The firm has since apologised, claiming the process was "completely safe and controlled".

The restart of the plant is in its final stage, with the Scottish Environment Protection Agency (Sepa) previously issuing a warning about elevated flaring, which “may fluctuate in size”.

Cowdenbeath councillor Darren Watt tweeted that “the flaring was the most intense I’ve ever seen”.

He also told the PA news agency: “The ‘fire’ is the flame from the elevated stack at ExxonMobil’s plant in Cowdenbeath.

“Although it’s pretty intense and a worrying sight, it’s not a fire.”

In a statement on Thursday, Sepa said: “Sepa is aware of fluctuations in the elevated flare at Mossmorran as part of the final stage of the facility restart and specialist officers continue to monitor.

“We’re working hard to address the root causes of ‘unacceptable flaring’, making flaring an exception rather than routine.

“The short and medium-term investment we’re requiring the operators to make, from noise reducing flare tips in 2020 and 2021 and planning, designing then delivering new ground flare capacity will make a real difference to local communities.”

A spokesman for ExxonMobil said: “Yesterday evening we deployed our elevated flare as part of our ongoing work to restart our operations.

READ MORE: Controversial Fife chemical plant to continue shut down until January

“This process is completely safe and controlled, and our team worked to reduce both the size and duration of the flare as quickly as possible.

“We exited the flare later in the evening following the safe completion of our work.

“We apologise to communities for any concern that this may have caused.”