The Cromarty Firth Port Authority confirmed last night that it is investigating a report of a mysterious “chemical cloud” release from the BP-contracted rig that was occupied by Greenpeace activists.
A local campaign group active in region claim the cloud has been spotted on “a number of occasions” by locals.
One Cromarty resident described the Transocean-owned rig as “looking like it was on fire”.
Another local man said the cloud was “really dense”.
The Paul B Loyd Jr rig is understood to be anchored in a special area of conservation and home to Scotland’s only population of bottlenose dolphins.
Several people claim to have witnessed a succession of releases between the 1 and 8 June 2019.
The report to the Port Authority is understood to have been made the day before the rig was commandeered in a five-day standoff between police and Greenpeace activists.
Arthur Bird, spokesman for local campaign group Cromarty Rising, said the release was likely “cement powder used in drilling operations”.
A spokeswoman for the Port of Cromarty Firth confirmed that it had “received one report” from a resident in the community on Saturday.
She also revealed that the port had been in contact with Transocean regarding the release, adding: “We’re currently investigating and won’t be able to say anything until we’ve completed that.”
Transocean did not respond when contracted by Energy Voice.
One resident, who did not wish to be named, said: “The first time I saw it was on the 1 June.
“Two of my neighbours and I honestly thought the rig was on fire because there was so much of what looked like smoke.
“The next incident was on the 8 June. Both were around 5pm in the evening.
“I called the port to tell them something strange was happening. It was a really heavy dense cloud.”
The Transocean rig was en route to work at BP’s Vorlich field before it was boarded by Greenpeace activists on Sunday.
Vorlich is a two-well development 150 miles east of Aberdeen.
Local activist Mr Bird added: “The issue for us is that latterly the firth has been used as a parking ground for North Sea scrap metal.
“These rigs are not enriching the local community they’re just stacked here as detritus.
“The Port Authority is really failing in its duty to monitor the contractors coming into the firth.”