Tighter welfare rules on lone parents and claimants with disabilities or health conditions have done nothing to force more of them into employment, according to a study by two Scots universities.

They also found that the new regime was ­ "neither dignified nor fair" and put those facing new assessments under "considerable strain."

Professors at the Employment Research Institute at Edinburgh Napier University and Stirling University are following dozens of people from across Scotland to see how changes to the system are affecting them.

They interviewed 43 people between September last year and January of this year, with 35 taking part in a second round of in-depth interviews between April and July.

They concluded: ­"Participants with a health condition or a disability, and those who were lone parents, reported that they wanted to be in work but faced considerable barriers to doing so, which were unlikely to be addressed by increasing conditionality."

Deputy First Minister Nicola Sturgeon said: "The system is not helping people without work find jobs and it is not making people with work better off in any real sense."