Climate change protesters in Edinburgh have been accused of putting lives at risk, after they poured an oil-like substance onto a busy dual carriageway.

Police say there has been a “worrying escalation” in the level of activity at the RBS HQ in Gogarburn, while activists have caused disruption at offices across Edinburgh, prompting 12 arrests.

An estimated 500 protesters have remained at the RBS campus, where a Climate Camp was created on Thursday in protest at the bank's alleged investment in fossil fuel firms.

And on Monday morning, as part of campaigners ‘day of action’, activists poured an oily substance, thought to be vegetable oil and diesel fuel, onto two main arterial routes in the west of the city.

At around 1pm, riot police were deployed at Gogarburn, while hundreds of officers are also guarding a number of buildings across the city centre following the oil incident.

The spill on the A720 and on the A8 westbound has now been cleared but police have advised motorists to exercise caution.

A police spokesman said: "This is an extremely reckless and dangerous act which could put many members of the public at risk.

"It is a worrying trend and disturbing escalation in the activities of the protestors.

 "While the Force facilitates peaceful protest, public disorder, damage to property or any other criminal acts will not be tolerated.

"It is obvious that the activists have changed their emphasis and we have considerable resources in place to respond in a proportionate and responsible manner.”

As police stepped up their resources in Gogarburn, a number of splinter groups of protesters were causing disruption across the capital.

One group unfurled a large banner across the A8, seven activists gained access to the roof of Forth Energy’s HQ in Leith to protest against the firm’s biomass proposals and seven people caused gridlock at the Gyle Industrial Estate after supergluing themselves to the entrance of the RBS executive carpark.

Another group also carried a large pig filled with an oily substance to the offices of Cairn Energy on Lothian Road, where they used the oil to paint the front of the building.

Meanwhile, management at a branch of the bank on Nicholson Street have been forced to turn customers away after three protesters superglued themselves into the doorway, blocking access.

The trio were arrested in the early afternoon, while a further five people were arrested after they glued themselves together and tried to occupy an office in the Leith Docks area. Two more activists were arrested on the Gogar flyover and another two were arrested at the city's Hunter Square.

A group of around 15 fellow protesters have also been distributing flyers outside the bank, accusing RBS of funding tar sands drilling in Canada, while other activists have reportedly set up camp outside an RBS branch on North Bridge.

A spokeswoman for the group insisted their aim was not to cause trouble for members of the public, but said that closing the bank was a success for the group.

She told STV News: “The last thing we would want is for individual customers to feel that we were targeting them specifically. We just want people to be aware of the choice they are making.

“It’s really easy just to go about your business and not think necessarily about the consequences of your own actions. We definitely want to target RBS itself rather than individuals, but it’s really important that we all understand where our money is going and, as customers of RBS, your money is being invested in tar sands in Canada, which is really unfortunate.

“So we’re asking customers, if you can, switch to a bank that has an ethical policy, or write to RBS and ask them why they’re investing in such destructive projects.”

The Nicholson Street protest also saw activists singing, dancing and playing musical instruments in the street. However, the spokeswoman said that she also supported fellow protesters who were using less peaceful methods.

She added: “Obviously, amongst protesters like ourselves, there are differences of opinion about how to move forward, but I think everyone is supporting the actions both of those within climate camp and those taking direct action.

“I think people should try to understand that they’re really not trying to harm or target anyone in particular, but really just to raise awareness. Because sometimes its so hard to get attention on these massively awful issues, unless some people go out there and really try to draw that attention.”

A total of 17 people have now been arrested since the camp was created on Thursday. On Sunday, two woman dressed in biohazard suits were arrested after breaching the police cordon. Police said they caused significant damage to the RBS building, with several windows smashed.

On Friday, a woman was arrested after supergluing herself to the building’s reception desk.

On Monday, the private nursery on the Gogarburn campus remained closed while RBS confirmed some staff would be working from home, describing the decision to allow staff to stay away from the office as a "sensible security measure".

A spokesman said: "We have provided some alternative locations for staff where appropriate.

 "We are constantly reviewing the situation and doing everything possible to protect the safety of our employees, customers and the general public."

Climate Camp claims that RBS, which is 84% government owned, has handed out a quarter of the cash given in a government bailout to coal oil and gas companies. However, RBS says it has acted responsibly, investing in a number of renewable energy and green firms as well as fuel companies.