PLANS to make substantial cutbacks to the housing benefit budget would force people to choose between food and heating and paying their rent, says Llanelli's MP.
The benefit, claimed by people on low incomes to help with the cost of housing, has come under scrutiny following reports of people receiving large amounts to cover London rents.
But MP Nia Griffith says the tabloid examples are "just fantasy figures" for most families in receipt of benefit in Wales.
She says the cuts will leave almost 50,000 households having to pay their rent from money intended for food and fuel.
"The grim truth is that families will have to choose between food and heating and paying their rent," said Ms Griffith.
"The cuts will risk leaving Welsh councils picking up the tab for homeless families evicted for non-payment of rent."
The cutbacks are proposed as part of the Government's controversial Welfare Reform Bill, which was passed last year and will come into force in April.
The bill includes reductions on the maximum allowance households can receive to cover the rent, and penalties for having a spare bedroom — dubbed a "bedroom tax".
Labour says these changes will hit many low-paid workers and low-income pensioners, as well as those who are out of work.
"Single people under 35 years old will be expected to move into shared accommodation, raising serious child protection concerns if they are separated parents whose children come to stay with them," said Ms Griffith.
"The Department of Work and Pensions has predicted that the average loss in Wales will be £9 a week, coming at a time when families are already struggling with rising food and fuel bills."
Housing charity Shelter Cymru has reported that the cuts could cost Wales more than £23 million a year.
Director John Puzey said the initial cost to councils of dealing with an approach for help by someone unable to keep up with housing costs was £167.
"Dealing just with new approaches would cost more than £1.4 million," he said.
"Then, if the household is found to be in priority need, it costs the council around £5,300 per case per year.
"That rises to £6,413 for households with children.
"We have argued all along that the housing benefit cuts are a false economy and will essentially just transfer spending from Westminster to Wales."
A Department for Work and Pensions spokeswoman said it had a discretionary fund of £280,840 to help Carmarthenshire families facing difficult situations in 2012/13.
"It's right that tenants in social housing who are living in homes that are larger than their needs make a contribution towards their rent or move to more appropriately sized accommodation — and this is exactly what people renting in the private sector do," she said.
"We do not expect many people to have to move as a result of these changes and Local Authorities can access £30m a year specifically to support disabled people with an adapted property and foster carers."