The decision came as a survey found record earnings for senior barristers, with a quarter of QCs earning more than £281,000 a year.

Conversely, the same survey found that 94% of young barristers were in the red, with 57% saying it would take them more than three years to clear their debt.

Some said they emerged from their postgraduate year at bar school owing £20,000 or more for fees and living expenses.

The council, concerned that entrants from poorer families were being discouraged from joining the profession, proposed a sliding scale levy on well-paid barristers to support students in financial difficulties through bar school.

The plan has been scuppered by opposition from commercial and chancery barristers, the two best-paid sectors of practice at the bar.

Chancery QCs charge £600 an hour, the survey reveals, and a handful of commercial and chancery silks earn up to £2m a year.

The Criminal Bar Association, whose members rely largely on the less well-paid publicly funded work, supported the proposal.

David Bean QC, the bar's chairman, said yesterday that the profession would now look at other ways of ensuring that able law students were not deterred by financial constraints.

"The debate has pushed this issue of access to the profession to the top of the bar's agenda," he said.

"I regard the issue as one of great importance to the future of the bar and it is vital that a solution is agreed in the next four months."

The survey, by BDO Stoy Hayward, also found that the introduction of a rule obliging chambers to pay pupils at least £10,000 a year from next year was deterring them from recruiting.

Some 700 students a year normally secure pupillages, a necessary stage for practice at the bar; the survey suggests that up to 139 pupillages could be lost next year.

At the top end, however, the profession was thriving.

Earnings for the top quarter of QCs rose to £281,000 from £268,000 two years ago.