It is believed at least 60 police officers – including some mounted on horses – are currently monitoring the situation at the North Killingholme site.
Superintendent operations for North Lincolnshire, Steve Graham, said: “Humberside Police are in attendance at the Lindsay Oil Refinery, North Killinghome, in response to a peaceful protest.
“At this moment in time there are about 800 peaceful protesters at the site.
“Police resources will be in attendance at the site as well as the surrounding area throughout the day.
“I would reassure our local communities that our main aim is to ensure the safety of both local businesses and public as well as those taking part in the protest in order to minimise disruption and to keep traffic flowing.
“I would appeal to those involved in this demonstration to remain peaceful. Whilst respecting the right of demonstration we will, however, consider any offences that may occur.”
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