One of the most senior judges in England and Wales has delivered a damning assessment of increased court fees.
Master of the Rolls Lord Dyson told MPs charges introduced in March last year risked denying access to justice to people on modest incomes and small businesses.
The Ministry of Justice has faced criticism from legal figures and campaigners over jumps in civil courts costs announced in recent years.
One of the most controversial changes was the decision, confirmed in January last year and implemented in March, to raise the fee to issue proceedings for the recovery of money to 5% of the value of all claims over £10,000.
Lord Dyson told the Commons Justice Committee on Tuesday that the so-called "enhanced fees" brought in last spring had "excited the most opposition".
He said: " I'm afraid that the risk of denying access to justice to a lot of people is so intense in those proposals."
Lord Dyson said he was "particularly concerned" about people on modest incomes who do not qualify for help with charges known as fee remission.
"They are the sort of people I think would be inevitably deterred from litigating. I don't say in all cases of course," he said.
"But I am particularly concerned about the small and medium enterprises.
"I take the example of the builder who is seeking £50,000 from a client, he now has to pay £2,500 up front as a condition of starting his claim."
He said this was a "massive increase" compared to the previous system, in which the builder would have faced a fee of around £800.
He went on: "It is bound to be severely deterring. Obviously not the really rich people - it won't deter them.
"But the small businesses, the sort of businesses actually this government says time and time again they want to encourage because they will be the engine that provides the growth that this country so needs - they are the very people many of whom are most at risk and who are most likely to be put off."
Ministers insisted when the fee hikes were introduced that more than 90% of claims were for less than £10,000 and would be unaffected. Charges were capped at a maximum of £10,000.