Savage Tory welfare cuts will rob working adults of hundreds of pounds a year, the Welsh government has warned.
It said Westminster's plans will cost adults in Wales an average of £500 a year.
In places such as Merthyr Tydfil and Blaenau Gwent the figure will be as high as £600.
The Con-Dems' slashing will see Wales lose about £930 million a year by 2016, and ministers warned of a "considerable impact" on the incomes of sick and disabled people.
Welsh Communities Minister Jeff Cuthbert said: "Some of these cuts are hurting low-income families at the very time they are seeing their incomes squeezed and are struggling to cover their everyday costs.
"The reality is we are going to see many get worse off and the wider economy of many communities will also suffer as people have less money to spend on local services and local shops.
"Within our budgets there is no way the Welsh government can step in to cover the gaps being created by the dismantling of welfare, but we will continue to do all we can to help the most vulnerable in Wales."
However the Coalition of Resistance seconded the Welsh government's concerns.
Spokeswoman Romayne Phoenix said: "Once again Westminster are happy to impose welfare cuts on the people of Wales with no regard to the devastation caused to individuals and their communities," with the Con-Dems' slash-and-burn policies also destroying communities in England and Scotland.
"Austerity economics fits the ideology of this coalition government but it is cruel, inhumane and irresponsible.
With people "already choosing between heating and eating or relying on pay-day loans, the quality of our lives is being sacrificed on the altar of the profiteers when a responsible government would be investing in jobs for the future and jobs to create decent public services."
A Department for Work and Pensions spokesman claimed that "welfare reforms will improve the lives of some of the poorest families."