An independent report has found serious flaws in the communication procedures of Scotland's environmental watchdog.
Sepa's communication problems related to its regulation of Dounreay
The inquiry into the Scottish Environment Protection Agency (Sepa) discovered problems relating to the regulation of the Dounreay nuclear power plant in Caithness.
It found that senior managers at the organisation "failed to address serious issues".
The report, which was commissioned by Sepa, also said communication between senior managers and its board were "ineffective".
However the study, carried out by Sir Laurence Hunter of Glasgow University, found no evidence of danger or increased risk to the environment as a result of the communication failures.
Following the inquiry, Sepa has made a number of changes to its internal procedures for regulating Dounreay.
Dr Campbell Gemmell, Sepa's chief executive, said: "I want to reassure people that there is no evidence that the environment has been put at risk.
"However, it is not acceptable for an organisation like ours to neglect the proper processes.
"I have prepared an action plan that will ensure we have robust procedures in place for carrying out our duties."
He added: "We are already taking positive action to improve our ways of working."
But anti-nuclear protesters reacted angrily to the revelations.
Lorraine Mann of Scotland Against Nuclear Dumping said: "Of course there was risk to the environment.
"Regulation is there for a purpose, if it's not done properly there is always a risk to the environment."
The inquiry was set up by Sepa after its board discovered that Dounreay's operator, the UK Atomic Energy Authority, had employed a consultant to investigate communication between the two organisations.
It emerged that staff of Sepa had signed up to the study without the board's knowledge.