The Solicitors Regulation Authority (SRA) has challenged the £150m cap on Tesco law licensing breaches recently set out by the Legal Services Board (LSB).

The SRA has questioned the maximum penalty recommended by the LSB last month, citing the miners' compensation case that saw 500 firms paid £1bn for acting for sick coalminers. A raft of firms involved later faced claims over their conduct in handling the work.

While the SRA acknowledged that potential fines of £50m for individuals and £150m for entities would act as a "significant deterrent", the regulator warned that the change in regime will "introduce new entrants to the market" and it may be dangerous to rely on current turnover figures to determine appropriate fines.

The SRA stipulated that "regulated persons should not profit from their misconduct" and questioned whether the proposed maximum penalty would cover all possible scenarios.

The SRA consultation response states: "A cap of £150m could be too low to deal with a scandal equivalent to miners' compensation, particularly if fewer firms gain contracts to carry out high volume work.

"£1bn was paid to 500 law firms in miners' cases. A similar scheme in the future might involve a much smaller number of firms with consequential rewards being much higher."

However, the SRA did agree that a maximum fine should take precedence over a calculation based on turnover that would differ in its impact depending on firm size.

Meanwhile, the £50m maximum penalty for individuals has been deemed by the body as "sufficient regardless of medium-term market developments".

The ABS regime, set to officially come into force on 6 October this year, will allow companies to invest in law firms and provide legal services outside of traditional partnerships.