Previous Climate Camps have been at Heathrow and a power station in Kent
Police have promised a low-key approach to planned climate change protests this week to avoid trouble that flared during the G20 summit.
The location of a Climate Camp will not be announced by demonstrators until later. A week of protests intend to disrupt targets in London.
Organiser Natalie Swift said: "Direct action is the aim - we are trying to disrupt the climate criminals."
It will be the first big test of the policing of protests since the G20.
Possible sites of the seven-day camp include streets in the City and St James's Park.
The protest is the latest attempt by climate-change activists to draw attention to industries and government departments who they say are damaging the environment.
It follows similar protests at this April's G20 London summit, where police were accused of a heavy-handed approach to policing.
Newspaper seller, Ian Tomlinson, who was not involved in the G20 protests, died during the demonstrations. Prosecutors were handed a file on his death earlier this month.
CAMP GATHERING POINTS
The Bank of England
The headquarters of oil company Shell in Waterloo, central London
The offices of BP near Picadilly Circus, central London
Stratford Station, near the site of the 2012 Olympics, east London
Offices of mining company Rio Tinto in Moorgate, City of London
Stockwell Tube Station in south London, where Jean Charles de Menezes was shot dead by police
Analysts think the encampment will be near one of six gathering points highlighted by the Climate Camp group.
Police said a 500-strong force would adopt a friendly "neighbourhood-style" approach in an attempt to avoid any G20-style trouble.
Officers are being briefed to "build relationships" with campers and they have also pledged not to use widespread stop and search tactics.
'Never say never'
But the Metropolitan Police's Ch Supt Helen Ball said she would not rule out moving the camp if the location was too sensitive.
She said, although it would be a major operation: "You can never say never to anything".
Ch Supt Helen Ball also admitted they were completely in the dark about the location.
She said: "We are looking at intelligence from open sources.
"But we have no intelligence as to the planned camp location."
Organisers expect up to 3,000 people, equipped with tents and sleeping bags, to attend the camp.
Will Geddes is managing director of ICP Group, a security firm advising one of the companies that fears it may be targeted.
Climate Camper Dave Lewis, 31, explains why he will be there
I have always been concerned about climate change and felt I should do something proactive. I'm really looking forward to it - we will need to strike a balance because it is a serious issue, but should also be fun as well. I went to the last Climate Camp in Kent. It was a brilliant vibe. The heavy police presence made everyone feel close together. I booked time off work to come. I have my tent and sleeping bag packed and ready!
Mr Lewis is an office administration worker
He said: "The camp will be somewhere within that list of targets.
"But they are spread right across London - making it very difficult for police who will find out at the last minute.
"Police will be doing as much as they can to discover where the location is.
"But it will be hard to do so. The organisers have been very crafty."
A Climate Camp spokesman said: "I have great faith that the location will be suitable - and defendable as well.
"It would not be in the police's interests to create a scene like that."
Asked how the Climate Camp location had been kept secret, organiser Natalie Swift said: "Not many people know and they won't until the last minute.
"It is out of necessity - police have been trying to disrupt camps for years."
Leaked plans show the organisers intend to target organisations such as the London Stock Exchange and the finance ministry.
Action may include gluing themselves to buildings and forcing their way into offices.
Ms Swift said they hoped to cause maximum disruption to whichever of the "dirty dozen" targets were selected, adding: "What they are doing is wrong and has to stop.
"If the government is not going to do it, normal people will have to step in."