A new body should be set up in Scotland to protect workers from abuse and exploitation by bosses, it is claimed.
Citizens Advice Scotland (CAS) is calling for politicians at Holyrood and Westminster to work together to create a Fair Employment Commission.
Over the past two years advisers in Scottish Citizens Advice Bureaux have dealt with some 107,000 cases where people claim to have been treated unfairly at work - almost 150 a day. However, CAS fears that could be the tip of the iceberg, with many people too afraid to report such treatment.
Susan McPhee, head of policy for CAS, spoke out as the organisation published its Fair Employment report. She said: "To address the problem longer term, we call today for a Fair Employment Commission - with powers to identify wrongdoing and to punish employers who flout the law and exploit their staff."
She said those who experienced problems at work were often low-paid and low-skilled workers, with many unaware of their rights, leaving them "vulnerable to unfair treatment by rogue employers".
She stated: "As a society we might have hoped that workplace exploitation was a thing of the distant past. Sadly, this report shows that many Scots are still being treated unfairly. Examples include illegal changes to contracts, unfair dismissal, low pay, withheld wages and victimisation of those who have tried to demand their rights."
In 2010-11 CAB staff helped with more than 11,000 issues concerning pay and entitlements at work and more than 5,000 new cases relating to redundancy. They also dealt with almost 8,000 new cases where people had been dismissed, with most of these involving unfair, constructive or wrongful dismissal.
Ms McPhee said: "Our evidence today shows that there are still some employers who are using the recession as an excuse to mistreat their employees. They feel they can get away with it because workers are terrified of losing their job."
The Fair Employment report said one of the "key features" of the recession had been that "many employers retained staff on less generous terms and conditions rather than making large numbers of employees redundant". While it said this was "usually preferable to redundancy", cutting workers' hours and wages could have "a significant impact".
Although there are a number of organisations people can turn to, the report argued the role of statutory bodies - such as the Health and Safety Executive and the enforcement division of the National Minimum Wage - was "far from comprehensive". Because these bodies have "narrow and closely defined" remits, there is "no statutory enforcement body to complain to for many workers".