Freedom of information laws are being eroded by a change to the way public services are provided, it has been claimed.
Information Commissioner Rosemary Agnew is concerned that there is a growing use of so-called arms-length organisations, set up by councils but without their direct control.
Their status means they are often exempt from the legislation and do not have to disclose the same range of information to the public.
Ms Agnew raised her concern as she published her first annual report since taking on the job.
"Freedom of information was introduced for a reason: to ensure that the delivery of public services and the spending of public money is transparent, open and accountable," she said. "It is simply not acceptable that citizens' rights continue to be eroded through complex changes in the delivery of services. This must be looked at as an immediate priority."
Her annual report shows a 24% rise in appeals to the commissioner. Of the total, 77% were from the public, 12% from the media, 6% from commercial organisations and 2% from the voluntary sector.
"The current economic situation is leading to an increase in freedom of information requests to authorities, as people naturally want to understand the reasons behind decisions that affect them. At the same time authorities are finding themselves with fewer resources to respond," Ms Agnew said.
"My priority as commissioner is to help the public make better-targeted, more effective requests while also developing resources to support public authorities in responding to those requests faster and more efficiently."
A Scottish Government spokesman said: "We are currently progressing a Freedom of Information Bill through Parliament, which will improve the system and make more information available to the public earlier.
"It is for individual Scottish public authorities to develop their own approach to handling FoI requests, in accordance with the FOI Act, and it is a matter for the commissioner to judge how they are dealing with FoI requests."