Mischief, mayhem and madness come to town

• RBS Gogarburn Climate Camp where the Rhino structure is being moved

The company was subjected to protests at its headquarters and at city branches, with several other banks and energy firms targeted.

Twelve people were arrested throughout the capital, with Lothian and Borders Police deploying a "significant" number of officers, including staff from other forces and British Transport Police.

While the vast majority of nearly a dozen incidents passed off peacefully, one unidentified group were singled out for criticism after pouring an oil-like substance over two of the capital's main arterial roads.

Police warned that the lives of the public were put at risk after a liquid similar to diesel or vegetable oil was poured over the carriageways on the City Bypass at around 9:30am, forcing the closure of the A720 at Bankhead and the westbound A8 for several hours.

The Camp for Climate Action (CCA), the umbrella protest body that has been spearheading a series of protests against RBS in Edinburgh, expressed "bewilderment" and said its members were not responsible.

A spokesman for RBS said there was a "minimal" staff presence at its Gogarburn headquarters after it encouraged employees to either work from home or an alternative location.

The degree of co-ordination on the part of CCA was unclear, with the group unaware of some protests taking place in the city centre.

It was the flashpoint on the City Bypass that proved the most controversial event of the day, and one which brought condemnation from police.

"This is an extremely reckless and dangerous act which could put many members of the public at risk," said a police spokesman. "It is a worrying trend and disturbing escalation in the activities of the protesters."

Some protesters also took a bridge over the A8 and glued themselves together, before unfurling a banner which read: "RBS using our money to f*** the planet."

City of Edinburgh Council staff cleaned the affected route and traffic was moving again at around midday.

• Brian Ferguson: Sound of sambas could be heard only yards from police in riot gear

• Day of chaos: timeline

Mike Crockart, the Liberal Democrat MP for Edinburgh West, said the demonstrations had taken an "ugly turn".

"The utterly irresponsible behaviour seen on public roads could have caused serious injury or worse, and all reasonable people will join me in condemning these actions," he said.

His Lib Dem colleague, Margaret Smith, the MSP for Edinburgh West, accused protesters of "recklessly endangering people's lives".

However, in a statement, the CCA said it was not aware who had carried out the stunt. It said: "The CCA have expressed bewilderment as to police claims of oil being spilled on a main road, and have no knowledge who was responsible for it if the incident did take place."

The organisation said it was "celebrating a successful day" overall.

At the RBS headquarters in Gogarburn, a presence of several hundred police officers was evident throughout the day, with dozens of vehicles forming a ring around the campus. At the nearby makeshift CCA camp, there were around 300 people in attendance, with more arriving as the day went on.

By 1pm, riot police took up position to the back of the main building, and officers assembled on the main access road to the site from the A8. People going in and out of the main climate camp were stopped and searched, and asked for their names and addresses. Two people were arrested at the fly-over at the Gogar roundabout.

One of the few staff members to make their way to work at Gogarburn said: "It was pretty scary seeing the violent scenes on Sunday. People just don't understand why they're targeting RBS."

Two hours later, demonstrators began mobilising a large "siege tower", inching their way towards the police line. Around 200 protesters followed the structure, and at around 4:30pm, four containers of a molasses-like substance were hurled, striking and staining the RBS building. At one point, the structure became entangled in a tree, and demonstrators had to saw part of it down.

At the Drummond House premises of RBS near the Gyle Shopping Centre, a group of around 15 activists arrived at approximately 8:30am to find a large police presence. The protesters partly blockaded the staff entrance to the building, unfurling a banner which read: "We won't pay for your crisis". Seven of the protesters had superglued their hands together in a chain.

Elsewhere, three RBS branches were forced to temporarily close as part of the day of action.

At the bank's presence on Nicolson Street, three protesters superglued themselves to form a barricade just inside the entrance, while a band sang a version Lady Gaga's song. Poker Face – which was renamed Dirty Oil – outside the bank and others danced in the road.

The branch reopened following the first incident at 10am, in which police made three arrests, but it was forced to close again mid-afternoon after more protesters, dressed in bin bags covered in treacle so as to resemble oil, made their way to the branch.

The RBS bank at Minto Street was also closed for several hours after bank staff arrived for work to find someone had superglued the locks together.

At around 2:15pm, the RBS North Bridge branch was targeted by a group of protesters and forced to close. A banner unfurled from scaffolding outside the bank read: "RBS funds & profits from climate chaos".

Campaigners later moved on from the city's banks to set up a protest site under the RBS-branded archway leading to the Fringe Festival on the Royal Mile.

Earlier, activists descended on the offices of Forth Energy in Leith, with two individuals scaling the roof and hanging banners which read: "Bio mass health hazard" and "Bio mass = climate change". According to the CCA, three people found their way inside the building at around 8am, with two others chaining themselves to the front entrance.

At around 9:15am, meanwhile, the Lothian Road offices of Cairn Energy were targeted by protesters, who created an "oil slick" using molasses. The oil-like substance was carried in a two-metre long container resembling a piggy bank with the RBS logo, which was left outside the firm, which explores, develops and produces oil and gas assets.

A spokeswoman for Cairn Energy said the firm did not fund oil exploration using borrowed money. A Clydesdale Bank branch in Lothian Road was also spray-painted by activists during the morning. Two people were also arrested in Hunter Square.