SINN Féin and the SDLP have clashed over the shelving of a £35m-a-year benefits scheme amid the political deadlock at Stormont.
The Irish News reported on Monday that civil servants have confirmed the Cost of Work Allowance (CoWA), aimed at tackling 'working poverty', cannot be implemented without ministerial approval.
It was to provide low-paid families with up to £690 a year until 2020 to help mitigate against Westminster welfare cuts.
Stormont officials said they are considering options for an alternative CoWA scheme after HM Revenue and Customs confirmed payments would be treated as taxable income, therefore reducing the net benefit claimants would receive.
However, they said it would be "for an incoming minister to decide" on the scheme's implementation.
The issue was confirmed in a letter from the Department for Communities to SDLP deputy leader Nichola Mallon.
The North Belfast MLA said it was a "disgrace" that families could not avail of CoWA, describing it as a "direct result of the political fall-out between the DUP and Sinn Féin".
"Rather than putting all of their energy into blaming each other for the political shambles we're in, the DUP and Sinn Féin should sit down, sort their differences over an Irish language act and put the needs of these families and the needs of people right across the north first," she said.
However, Sinn Féin North Belfast MLA Carál Ní Chuilín hit out at her constituency rival's comments.
She blamed the issue on the British Treasury treating the allowance as taxable income, and said that "to claim this is due to 'differences over an Irish language act' is disingenuous and quite disgraceful".
Ms Ní Chuilín claimed Ms Mallon's comments "do a huge disservice to the families who need this support and to those who are rightly entitled for language rights to be implemented".
Northern Ireland has not had a power-sharing government since the DUP and Sinn Féin-led executive fell apart over a year ago.
The parties insist they want to restore devolution, but disagree over issues including same-sex marriage and an Irish language act.
Responding to the criticism, Ms Mallon said the scheme cannot be implemented without a minister, and "anyone writing to the department on this issue will have that in black and white".
