Tenants in south Wales taking part in a trial of the UK government's benefits reforms have seen rent arrears rise seven-fold to £140,000 in seven months.
Landlords in the pilot area in Torfaen warn evictions could increase if the trend continues after the system for paying benefits is fully adopted.
Housing benefit is currently paid to the landlord but it will transfer to the claimant under the reforms.
The minister in charge said it would help people to manage finances better.
However, an investigation by BBC Radio Wales' Eye on Wales programme highlights concerns that changes to the benefits system - beginning with the introduction of the so-called "bedroom tax" from April - could push both social housing tenants and landlords into financial difficulties.
Torfaen is one of six areas where the Department of Work and Pensions is running what it calls "demonstration projects" ahead of the introduction of the UK government's flagship welfare reform of Universal Credit in the autumn.
Eye on Wales has learned that the first group of Torfaen tenants selected for the trial saw their total arrears rise from around £20,000 to approaching £140,000 in the seven months from July to January.
BBC
