Plaid Cymru concern at rent payment help claims after benefit changes
Big increases in people applying for help to pay their rent have been reported following changes to housing benefit.
Many councils in Wales received more claims for financial help in the first two months after the changes than in the entire previous year.
Plaid Cymru, which carried out the research, blamed UK government changes to housing benefit.
The UK government said it was monitoring its reforms closely.
Since April the UK government has cut the amount of benefit available to housing association or council tenants with empty bedrooms.
Critics call it a bedroom tax, but the government says removing a "subsidy" for spare rooms means benefits are based on the amount of space that tenants need, bringing the rules in line with the private sector.
Councils can make discretionary housing payments to help council tax and housing benefit recipients cover their rent.
Tenants can apply for the money if they fall short because of changes to their benefits.
Figures obtained by Plaid from 21 of Wales' 22 councils show 11 of them got more claims for discretionary payments in the first two or three months under the new benefit system than in the whole of the 2012/13 financial year.
- In the Vale of Glamorgan requests rose from 136 in 2012/13 to 524 for April to June this year.
- Wrexham had 219 applications in the first two months of this financial year, compared to 59 in the whole of 2012/13.
- In Swansea - where 3,024 people were affected by the benefit changes - there were 802 in 2012/13. There were 820 in April and May 2013 alone.
Plaid assembly member Jocelyn Davies, the party's housing spokeswoman, said: "These figures reveal the true impact of the UK coalition government's policies on social housing tenants.
"They are hitting vulnerable people hard.
"It is clear that many people have turned to local authorities for top-up help with their housing costs after seeing their benefit cut."
Meanwhile, a cap of £26,000 pounds on the total amount of benefits people can receive comes into force in Cardiff on Monday.
It is estimated it will affect around 300 households.
Last month the UK government announced £875,000 for Gwynedd, Ceredigion and Powys councils to help with discretionary payments in the least densely populated parts of the country.
A Department for Work and Pensions spokeswoman said: "It's simply not affordable to pay housing benefit for people to have spare rooms in social housing, when there are millions of households on the social housing waiting list and in overcrowded homes.
"We have no evidence that councils are running out of discretionary housing payments but as with any major reform, we are monitoring it closely - including watching how councils are spending the extra funding that we are providing to support vulnerable people."