The first five presidents of the International Criminal Court's oversight body on Thursday called for a review of the institution's functioning, following its April 12 decision not to investigate possible war crimes committed during the 17-year Afghan war, allegedly by militants, the US army, Central Intelligence Agency and Afghan armed forces.

According to the United Nations, at least 32,000 civilians have been killed and another 60,000 wounded in the last decade when the organisation began compiling the data.

ICC prosecutors in 2006 opened a preliminary investigation into war crimes and crimes against humanity committed in Afghanistan since 2003. In 2017, chief prosecutor Fatou Bensouda asked judges to allow a full-blown probe not only into the Taliban and Afghan soldiers, but also international forces, particularly US troops and members of the Central Intelligence Agency.

The court began collecting material for the case between Dec 2017 and Feb 2018, and has received over 1 million statements from Afghans who say they were victims.

'Reasonable basis to probe war crimes'

However, the Hague-based court in a statement accompanying its April judgement, said that the investigation "at this stage would not serve the interests of justice", and that with its limited budget, it needed to prioritise resources on "activities that would have a better chance to succeed".

The ICC ruling issued earlier this month stated that the prosecution "alleges that the Taliban and other anti-governmental groups can be held responsible" for incidents included in the findings of the United Nations Assistance Mission in Afghanistan and the Afghan Independent Human Rights Commission.

The prosecution also believed there is "reasonable basis" to believe that the US armed forces, CIA and Afghan National Security Forces were allegedly involved in various war crimes.

With regards to 'other acts' by members of international armed forces, the ruling states that the prosecution has "not reached 'a determination that there is a reasonable basis to believe, at this stage, that crimes within the jurisdiction of the Court have occurred', in particular because the information available was either insufficient or could not be analysed in time.

The ruling concludes that "an investigation into the situation in Afghanistan at this stage would not serve the interests of justice and, accordingly, rejects the request".

'Devastating consequences for peace'

The group of former ICC presidents, which includes former United Nations High Commissioner for Human Rights Zeid Raad al-Hussein, called for an independent assessment of the court's functioning to be carried out by a small group of experts.

"We are disappointed by the quality of some of its judicial proceedings, frustrated by some of the results, and exasperated by the management deficiencies that prevent the Court from living up to its full potential," said the group in a post on the Atlantic Council's website entitled 'The International Criminal Court Needs Fixing'.

"The rejection of an investigation of war crimes and crimes against humanity in Afghanistan by the Court’s judges on April 12, citing a lack of confidence that the Court could successfully carry out the job, is a prime example of why [...] an independent assessment of the Court’s functioning by a small group of international experts is badly needed," the post said.

"From Syria to Myanmar, from Yemen to South Sudan, we are witnessing conflicts fought with cynical disregard for human dignity and international law. This has devastating consequences for the prospects of sustainable peace," the officials said.

"But the powerful impact of the Court’s central message is too often not matched by its performance as a judicial institution. We are disappointed by the quality of some of its judicial proceedings, frustrated by some of the results, and exasperated by the management deficiencies that prevent the Court from living up to its full potential. That is why we think an independent assessment of the Court’s functioning is needed," the statement said.

US threatens ICC officials, judges

The State Department in a statement had said that the "United States will take the necessary steps to protect its sovereignty and to protect our people from unjust investigation and prosecution by the International Criminal Court."

US Secretary of State Mike Pompeo had said last month that Washington would revoke or deny visas to ICC staff seeking to investigate alleged war crimes and other abuses committed by US forces in Afghanistan or elsewhere and may do the same with those who seek action against Israel.

The United States has also threatened to arrest and sanction judges and other officials of the International Criminal Court if it moves to charge any American who served in Afghanistan with war crimes.

ICC chief prosecutor Fatou Bensouda's US visa was revoked in what appeared to be evidence of a crackdown on the global tribunal by the Trump administration which has been outspoken about the court's investigation.

White House National Security Adviser John Bolton has called the Hague-based rights body "unaccountable" and "outright dangerous" to the United States, Israel and other allies, and said any probe of US service members would be "an utterly unfounded, unjustifiable investigation".

"If the court comes after us, Israel or other US allies, we will not sit quietly," Bolton said.

He said the US was prepared to slap financial sanctions and criminal charges on officials of the court if they proceed against any Americans.