Climate change activists who scaled two 300ft chimneys at West Burton power station have said they are "in it for the long haul" and have enough supplies to last a week.
A number of protestors from the group No Dash for Gas gained access to the site, near Retford, in the early hours of Monday morning.
They then scaled the power station's chimney's and have set up camp inside, suspending their tents from ropes.
Five people have already been arrested on suspicion of aggravated trespass - all of them women and from either Manchester or Leeds.
WATCH: Exclusive video footage of the protesters as they make their way to the smokestacks
The group have been keeping followers up to date with their protest via Twitter and on their website.
A blog entry on their site read: "The occupation fires the starting gun on a huge nationwide battle over Britain's energy future, with activists determined to stop government plans for a new dash for gas. They are calling instead for a high-tech carbon-free electricity system.
"The night-time incursion was launched at 2am when the raiders got through the security fence. Under cover of darkness fifteen of them crossed the expanse to the chimneys then split into two groups and began the 300ft climb to the top. They are now building barricades to defend their positions. They have enough supplies with them to last at least a week and say they're in it for the long haul."
Police have warned the group they will be arrested.
Paul Broadbent, assistant chief constable of Nottinghamshire police, said: "We have no choice but to police the protest, to try and bring it to a successful and swift conclusion and to ensure that everyone's safety at the power station is protected – including that of the protesters.
"That is already proving a drain on police resources – and if the current staffing levels are maintained day and night for the next week, that will cost in the region of £200,000 – excluding petrol, overtime payments, and other factors.
"Of course people have a legal right to protest – but they must do that lawfully. In trespassing into the power station, scaling chimneys and effectively taking up residency, the demonstrators have acted illegally. There are 101 ways to protest lawfully but breaking into someone else's property is not one of them.
"I make no comment on the motivation, or cause, of those taking part in the protest. But I do wonder whether the tax payers of Nottinghamshire would want scarce police resources to be occupied in policing this protest."
