The government was accused of "rampant cronyism" last night after a barrister from Cherie Blair's law firm was named as the head of the Crown Prosecution Service.
Ken Macdonald, a founding member of Matrix Chambers, where the Prime Minister's wife practises under her maiden name Cherie Booth, will become Director of Public Prosecutions in the autumn.
Mr Macdonald, 50, has handled cases whose subjects have ranged from child abuse and City fraud to gangland violence and international terrorism, and has represented Irish republicans and alleged al-Qa'ida terrorists. More recently, as chairman of the Criminal Bar Association, he attacked the Government's "alarming" moves to curtail the right to trial by jury.
A spokeswoman for the CPS said Mr Macdonald had been appointed to the £145,000-a-year post by a panel of impartial senior civil servants and legal figures. She said: "The selection process was completely transparent and accountable. It was an open competition. The fact he comes from a distinguished chambers signals that he is a leading barrister, but the chambers he comes from had no other bearing on the appointment."
David Davis, who shadows the Deputy Prime Minister for the Tories, denounced the choice as "astonishing".
He said it came after the appointment of Lord Falconer of Thoroton, Tony Blair's former flatmate, as Lord Chancellor, in succession to Lord Irvine of Lairg, regarded as the Prime Minister's mentor.
"Under this Government there appears to be no institution which is safe from the Prime Minister's rampant cronyism," Mr Davis said.
"There are certain parts of the British constitution that should be totally protected from this kind of behaviour and paramount among them should be the judicial system that only two months ago the Prime Minister claimed he wanted to be free from all forms of political interference."
Simon Hughes, the Liberal Democrat home affairs spokesman, said: "I have no reason to doubt Ken Macdonald is up to the job, but this is a provocative appointment and we will need assurances the decision was impartial and based entirely on merit.
"This is becoming more and more a government of who you know rather than what you know. Whether or not it is intended, jobs increasingly appear to go to people who are 'one of us'."
Announcing the appointment, Lord Goldsmith, the Attorney General, said: "[Mr Macdonald] brings to the job a distinguished record in the criminal law, strong leadership qualities and a commitment to a firm and effective CPS, prosecuting in the public interest ... I look forward to working with him to continue the reform of the CPS and to enhance the role and status of prosecutors."
Mr Macdonald, who is married with three children, was educated at St Edmund Hall, Oxford. He was called to the Bar in 1978 and took silk in 1997. As well as being a founder member of Matrix Chambers, he has sat as a part-time Crown Court judge since 2001.
Mr Macdonald, who succeeds Sir David Calvert-Smith, said: "This is obviously one of the most challenging and exciting posts in the criminal justice system and I am very much looking forward to taking it on."