Scotland's Social Security Secretary has called for "radical" reform of the personal independence payment (PIP) system across the UK.
Angela Constance highlighted figures showing almost two-thirds (65%) of disabled people who dispute their PIP award are successful.
The Scottish Government is currently consulting on a Scottish social security system with new powers, including over PIP, due to be devolved to Holyrood.
Ms Constance said that, in the meantime, the UK Government should move to address a "deeply-flawed" system which she claimed was failing to treat people with dignity and respect, and lacked consistency.
She was responding to the UK Government's second independent review of how the assessment for PIP is working, led by Paul Gray, chair of the Social Security Advisory Committee.
Ms Constance said: "It is absolutely staggering that 65% of people who dispute their PIP award are successful in their appeal of that decision.
"Not only does that highlight a deeply-flawed system, but it shows very clearly the number of people subjected to a highly-stressful, often prolonged, process to get the support they need and are entitled to.
"It completely fails to treat people with the dignity and respect that, not only do they deserve, but they should have a right to expect from a system that was set up to help them.
"The unacceptably high appeal and overturn rate, the lack of information available, the confusion over different types of support available and the inconsistent decision-making all add up to a wholly unacceptable situation.
"When we have powers over disability benefits, we will put dignity and respect at the heart of everything that we do.
"We will reform the assessment procedures to ensure they work for service users and are committed to working with disabled people through the consultation and beyond, to get this right.
"In the meantime, I hope that this second review will take on board the points we raise - although more importantly the views of the many disabled people who have also responded directly and indirectly to this review - and radically reform PIP to make it fit for purpose and ensure it provides the help it should do to the people who need it most."
A spokeswoman for the Department for Work and Pensions said: "We introduced personal independence payment (PIP) to replace the outdated disability living allowance. PIP is a better benefit which is tailored to suit each individual's needs.
"We want to ensure people get the support they need and the independent review is part of our commitment to make sure the system is working as we intended."
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