Police searched people entering the camp site near the power station
The government has defended a decision to pass on police intelligence about a planned protest at a power station.
E-mails obtained by the Lib Dems show the Department for Business (Berr) gave details of a planned 2008 climate camp at Kingsnorth, in Kent, to owner E.On.
MP David Howarth accused the department of treating police as an "extension" of E.On's private security operation.
But a government spokeswoman said the intention was "to ensure the security of the country's energy supplies".
The information was passed on from Berr civil servants to E.On ahead of the Camp for Climate Action protests, which took place over a week at Kingsnorth last August against plans for a new coal-fired power station.
The information included details of the movements of protesters and information from the Police National Information and Co-ordination Centre.
One e-mail refers to a copy of a "strategy" document which is said to be attached to the e-mail and was written and circulated by a group within the environmental protest community.
The email adds: "If you haven't seen it then you will be interested in its contents."
Liberal Democrat MP David Howarth obtained the information from the department following a Freedom of Information request.
He said: "It is as though Berr was treating the police as an extension of E.On's private security operation.
"The question is how did that (police) intelligence get to Berr? Did it come via the Home Office or straight from police? And once they had got this intelligence, what did they do with it?
"These e-mails show the complete blurring of the line between public and private interests. It is worryingly reminiscent of the corporate state."
Climate Camp spokesman Peter McDonnell also demanded to know how intelligence had been passed on.
He said: "There are some really important questions that need to be asked. We demand to know who passed on this information; it's completely unacceptable in this day and age."
A government spokeswoman said the department was looking into how the information was disseminated.
But she said the intention of sharing police intelligence had not been to disrupt the protest, but to ensure the security of the country's energy supplies, which she described as "prudent planning".
She added: "Given the potential threats to the security of energy supplies posed by the protests, it is only right that the government liaised with the police and the owner of the power station to exchange factual information and discuss contingency plans."
E.On is planning the UK's first new coal-fired power station for 24 years
A spokeswoman for E.On said it was "normal practice" for such information to be shared between energy companies, government departments and the police.
She added: "We absolutely respect people's right to protest peacefully and lawfully.
"However, it is clear that there are some groups which very publicly aim to disrupt the safe operation of our sites, in which case our priority will always be for the safety of everyone involved."
The row over intelligence is the latest of several surrounding the policing of last August's Kingsnorth climate camp, when around 1,000 people protested against the planned coal-fired power station.
Some 1,500 officers were called in from 26 forces as part of the £5.9m policing operation - described as "disproportionate" by the Liberal Democrats.
Police have already been criticised for an allegedly heavy-handed approach to the protesters, and also for exaggerating the extent of police officers' "injuries" - some of which were later found to have been caused by sunstroke and insect stings.
Complaints about the treatment of the protesters in Kent have now been referred to the Independent Police Complaints Commission (IPCC).