There are currently 435 criminals in the South Tyrone and Fermanagh court area under threat of jail for dodging financial punishments.
The total, the third highest in Northern Ireland, has prompted claims that some offenders are being allowed to escape justice.
DUP MLA Lord Morrow said the justice system was failing to deliver.
“If someone goes to court, gets fined and then doesn’t bother paying it – what sort of justice is that?” he said.
The figures were released by Justice Minister David Ford following an Assembly question by Lord Morrow.
In previous years offenders may have served short prison sentences if they did not pay their fines.
However, a recent legal ruling stated that defendants should have a default hearing before the court decides how to deal with an unpaid fine.
Mr Ford said he intended to bring forward legislation to establish a new fine collection and enforcement service to increase the range of collection and enforcement options.
However, Lord Morrow, who branded the extent of unpaid fines as “staggering”, said it had come far too late.
“These figures are literally staggering – it is unbelievable that it has got to this stage, and the minister needs to explain what is going on,” he added.
“This cannot be acceptable and I intend to pursue it to ascertain just how this whole issue has got so out of control.”
Across Northern Ireland, Some 45,953 fines remain unpaid.