Cuts in legal aid fees paid to lawyers are a "real threat" to the criminal justice system in England and Wales, a leading barrister has warned.

Nicholas Lavender QC, the new chairman of the Bar Council which represents barristers, says he fears that fee reductions will discourage lawyers from working in criminal courts and make the system "less effective".

He says barristers have a duty to "speak out" against changes planned by ministers.

"The actual and proposed reductions in both the scope of legal aid and the rates paid for legal aid represent a real threat to our justice system," says Mr Lavender, in an article in legal magazine Counsel.

"The fees paid to advocates for conducting criminal cases in the crown courts have been reduced by 27% in the last six years. Yet we now face the prospect of still further cuts, including a 30% reduction in the fees paid for the most difficult cases, which came into effect last month. And the reductions currently being implemented in fees in some civil cases are more than 50%.

"If we are to continue to have an effective system for dealing with serious criminal cases, then we cannot create such huge incentives for people to give up, or not to engage in the first place in, criminal advocacy.

"The result will be longer trials, and more successful appeals, adding to costs rather than saving money and making the system less effective either at convicting the guilty or ensuring that those wrongly accused go free."

Mr Lavender, who was born in Royston, South Yorkshire, and comes from a mining background, added: "Our duty is to speak out against these changes, clearly and consistently."

Earlier this week thousands of lawyers refused to attend courts in a number of cities in England and Wales in protest at legal aid cuts.