Recently unemployed adults may have to wait five weeks before they get any benefit payments, according to a new report.
The report, published ahead of the latest unemployment figures, said the new five-week wait will apply to anyone making a fresh claim for social security benefits.
The union organisation said it was a "new and deliberate delay" which could distract new claimants from looking for work and drive them into the hands of payday loan firms.
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Douglas Ross has been accused of a "perverse sense of priorities" after it was confirmed he will be at the Nou Camp not the Commons.
Following criticism from MPs and campaigners, the work and pensions secretary said the helpline would be free by the end of the year.
The unemployment rate fell to 1.4 million, a rate of 4.3%, in the three months to August - the joint lowest level since 1975.