A Russian court has postponed the trial of the dead lawyer Sergei Magnitsky in the latest move to drag out the controversial case.

Magnitsky, the first person to be tried posthumously in Russia, stands accused of tax evasion, alongside his former employer, London-based investor William Browder. Magnitsky died in pre-trial detention in 2009.

Browder has been banned from entering Russia. The head of the investment fund Hermitage Capital was accused of tax evasion after falling foul of the Russian government.

Investigating the charges in 2008, Browder's auditor and lawyer, Sergei Magnitsky, discovered that police and tax officials had colluded to steal Hermitage's tax payments for their own enrichment. The case has come to exemplify Russia's corrupt justice system.

Dozens of journalists packed a tiny courtroom in central Moscow on Monday to hear the opening of the case. A cage with thick bars, designed to hold the defendants, stood empty.

Magnitsky's relatives and their lawyers have refused to take part in the trial, calling it a mockery of justice.

The court appointed two lawyers to stand in their stead, but neither showed up to the hearing on Monday. They had petitioned the court to delay the hearing until May, claiming to have read just five of the 60 volumes of dense texts that comprise the state's case against Magnitsky.

The judge approved a petition by state prosecutors to postpone the hearing until 22 March instead.

Russia's supreme court approved posthumous trials in 2011 with the aim of providing a way for relatives to clear the names of family members.

Magnitsky's relatives have opposed the trial and argue that it cannot go ahead without their approval.

Magnitsky died after being denied medical treatment for ailments he developed while awaiting trial. The Kremlin's human rights commission later found evidence he had been beaten.

The only person tried in relation to his death, a prison doctor, was acquitted last year.