A "deeply worrying" number of magistrates have resigned in protest against the criminal courts charge, according to the head of the Magistrates Association (MA).
The Independent said sources at the MA suggested more than 50 had quit the bench over the levy, which was brought in by the coalition government and is designed to ensure that criminals pay towards the cost of their court case.
The lobby group's chairman Richard Monkhouse said his members were concerned about the "fairness" of the charge.
Justice Secretary Michael Gove told MPs on Tuesday he will review the criminal courts charge introduced by his predecessor Chris Grayling, as he acknowledged "widespread concern" about its operation.
Mr Gove stressed that the charge, which can be up to £1,200 for criminals in England and Wales, should only be levied after other fines have been paid and that it should be linked to the offender's ability to pay.
Mr Monkhouse told the Independent: "It is deeply worrying we are losing such numbers of experienced magistrates.
"The issue has caused a level of concern among our members that I have not seen before and they tell us that it is about fairness. They're reporting a clear influence on pleas with the very strong temptation for defendants to plead guilty to avoid a higher charge.
"When coupled with the fact we do not believe the vast majority of charges will ever be recovered because your average defendant cannot pay, we're reiterating our call for the Lord Chancellor to grant an urgent review and to give magistrates discretion on its case-by-case application, including means testing."
Defendants who plead guilty in magistrates court would be liable to pay a maximum of £180 but the charge rises to up to £1,000 for those who are found guilty after a trial by magistrates.
A Ministry of Justice spokeswoman said Mr Gove was referring to a review that will begin in April 2018 and which was already written into the legislation implementing the criminal courts charge.