Sudan’s justice minister, Ali Mohamed Osman Yassin, formed the court through a national decree. He was quoted by local media as stating that the court was "considered a substitute to the International Criminal Court".

On 18 June, the Sudanese court started hearing the first cases of 160 people accused of committing crimes in the states of North, West and South Darfur, the official Sudan News Agency (SUNA) reported.

Christian Palme, public information adviser for the office of the prosecutor at the ICC, told IRIN on Thursday: "Before the prosecutor decided to take on the Darfur case, he first analysed the admissibility of the case, which included ICC complementarity with what the Sudanese legal system was doing."

He added: "Given that the prosecutor would focus his investigations on individuals who bear the greatest criminal responsibility for crimes committed in Darfur, the analysis concluded that an ICC investigation would complement [the work of] the Sudanese judiciary."

On 14 June, the UN Special Representative of the Secretary-General for Sudan, Jan Pronk, said the establishment of the special court was "positive, but it cannot be a substitute for the International Criminal Court."

Announcing the formation of the Sudanese court the same week that the ICC started its own investigations was "interesting timing", according to Pronk, who suggested that the two courts operate side by side.

The Ministry of Justice criticised Pronk's remarks, saying the Sudanese criminal court would be a substitute to the ICC.

"ICC article 17 stipulates that it can refuse to look into any case if investigations and trials can be carried out in the countries concerned except if they are unwilling to carry out the prosecutions," a ministry statement said.

The UN Security Council, in a resolution on 31 March, referred suspected criminal acts committed in Darfur to the ICC prosecutor in The Hague. The decision required Sudan and all other parties to the conflict to cooperate with the court.

The ICC treaty, which Sudan is not a signatory to, states that any defendant tried in fair and credible national trials cannot be retried by the ICC. The Sudanese prosecution, however, has identified only small-time criminals rather than the senior officials likely to be indicted by the ICC so far.

The first persons standing trial in the new court were accused of looting a bus and other vehicles carrying more than 100 people outside Nyala in December last year.

ICC Chief Prosecutor Luis Moreno-Ocampo said in an earlier statement that the investigation would be impartial and independent.

"The investigation will require sustained cooperation from national and international authorities. It will form part of a collective effort, complementing African Union and other initiatives to end the violence in Darfur and to promote justice," he said.

Sudanese President Umar al-Bashir has stated previously that his government would not hand over any of its citizens for trial outside the country. He said Sudan's own judiciary was qualified and ready to try those accused of any violations in Darfur.

In April, the country's Council of Ministers declared its "total rejection" of UN Security Council Resolution 1593, which called for those accused of war crimes in Darfur to be brought to trial before the ICC. The Sudanese council said the court lacked "justice and objectivity".

"We fear that the establishment of the special court may just be a tactic by the Sudanese government to avoid prosecution by the International Criminal Court," said Kolawole Olaniyan, director of Amnesty International's Africa Programme in a statement.

"What we have here is a court system that is willing to silence newspapers and aid workers who are attempting to speak the truth about human rights violations in Sudan. How can we trust that same system to bring to trial those accused of these violations?" he asked.

In a statement on 16 June, the chief justice of the Sudanese Supreme Court, Jalal Eldein M. Osman said: "We emphasise that the Sudanese judiciary has always lived to its oath, is capable, willing and committed to shoulder full responsibility in the establishment of justice and restoration of rights."

"You can have it both ways," Pronk observed, and referred to the International Criminal Tribunal for Rwanda in Arusha and the national court in Rwanda’s capital, Kigali, which operate alongside each other.

"It [the ICC] is there now, and so you have to do it both ways. Do it both ways in such a manner that indeed a combined result is an end to impunity as soon as possible," he concluded.