Protesters who set up camp outside the Royal Bank of Scotland's Edinburgh headquarters have denied they caused an apparent oilslick on a busy road in the capital.

Climate Camp activists demanded an apology from Lothian and Borders Police over claims they were responsible.

The force said a substance appearing to be vegetable oil or diesel had been poured on to the A8 last Monday, and linked it to the protest camp.

But the protesters have denied knowledge of the spill - and sent a letter to the force asking it to apologise.

The letter states: "This has amounted to a smear campaign against Climate Camp on the grounds of an unsubstantiated implication of putting 'many members of the public at risk'.

"The lack of due process and evidence behind these public accusations represents a violation of the responsibility of the police to behave with fairness, integrity and impartiality toward the public."

A spokesman from the Climate Camp said: "We do take direct action against the causes of climate change and the severity of the climate crisis sometimes necessitates breaking the law.

"However, our actions have always been targeted at climate criminals - banks, corporations and governments - and have never aimed to endanger the public."

No-one from the force was available to comment.

At the time, a spokesman described the incident as "an extremely reckless and dangerous act which could put many members of the public at risk", adding: "It is a worrying trend and disturbing escalation in the activities of the protesters."

Most employees at RBS's Gogarburn headquarters were told to stay at home last Monday on a "day of action" by the activists. On the Sunday, windows were smashed at the complex.

Other incidents saw attacks on the offices of energy firms in Edinburgh. One activist superglued herself to a desk inside RBS's headquarters while others attached themselves to its gates. More protesters targeted city-centre branches.

Last week councillor Iain Whyte, convener of the police board, said protesters who broke the law should pay for some of the estimated £100,000 bill for policing the demonstration.