THE long-delayed Chilcot report could inform investigations into alleged war crimes in Iraq, according to the chief prosecutor of the International Criminal Court (ICC).

The Hague-based court is undertaking preliminary enquiries into allegations that British troops systematically abused hundreds of Iraqi detainees from 2003-08.

The claims include the unlawful killing of more than 250 civilians, including 47 said to have died in UK custody, and more than 1,000 allegations of torture and ill-treatment, rape, other sexual violence and denial of a fair trial.

War-crime allegations have been rejected by UK authorities, whose own Iraq Historic Allegations Team found just one instance of abuse in five years.

The ICC dismissed an initial complaint about British troops in 2006, concluding the 20 cases reported were not grounds for action, despite holding “reasonable belief” that crimes including wilful killing and inhuman treatment had taken place.

However, that number rose after a 250-page complaint by Public Interest Lawyers and the European Centre for Constitutional and Human Rights, prompting ICC chief prosecutor Fatou Bensouda to reopen the file in 2014.

Now she says the conclusions of the £10 million Chilcot report, expected to be made public this summer, may provide leads in any prosecution. On a visit to Scotland, Bensouda told The National such reports by domestic inquiries are not taken as evidence but “can provide useful leads”.

She said: “With respect to UK and Iraq, two years ago I opened preliminary investigations. This process is ongoing, the UK is cooperating with my office and we are looking at all the information.”

Families of UK personnel killed in Iraq are among those who have called for former Prime Minister Tony Blair to be prosecuted for war crimes, with similar calls made against David Cameron for British air strikes in Syria.

However, Bensouda said: “There are always calls for Mr X or a particular leader to be investigated but this is not how the office works.

“We look at situations. We follow the evidence leading us to the person bearing the greatest responsibility. There may be lots of media calls or a lot of private calls saying ‘you should pursue this leader or that leader’ but my office does its work based solely on the evidence.

“We try to explain how the court works, how it acts, where it intervenes and where it cannot, so people at least understand the expectations are high, but we really have to manage those expectations.”

The ICC’s jurisdiction covers states that have signed up to its founding treaty, the UN-negotiated Rome statute, and citizens of those countries, and handles only the most serious cases involving war crimes, crimes against humanity, crimes of aggression and genocide.

Active investigations are only ordered where domestic authorities are not acting on allegations, or where process has stalled and is not expected to conclude.

This rule led to the recent decision to work towards prosecutions for atrocities said to have been committed in the conflict in South Ossettia in 2008.

Fighting between Russian, Georgian and South Ossettian forces lasted a matter of days but is said to have forcibly displaced up to 18,500 ethnic Georgians, with a disputed number killed.

In January the ICC said there is a “reasonable basis” to believe crimes against humanity such as murder, persecution and forcible transfer of population had taken place, plus attacks on civilians and wilful killing.

The move was only possible after proceedings by Georgian authorities ground to a halt and marks the ICC’s first major investigation outside Africa.

Bensouda, from Gambia, said hers is a “court of last resort” which can “complement” national jurisdictions but not replace them.

She said: “Under the laws we cannot proceed with investigations or prosecutions if the national authorities are already undertaking or have genuine domestic proceedings.

“Until early last year this seem to be the case with Georgia. The timing of this by the ICC has largely been determined by the pace and eventually the lack of proceedings.” She added: “It shows that the office is completely independent. I will not hesitate to open investigations if the jurisdictional and legal requirements have been met.”

The ICC caseload is heavy and building, with teams dealing with “situations” involving leaders from Congo, the Central African Republic, Kenya, Mali and more.

As well as preliminary examinations on Colombia, Afghanistan, Palestine and others, Bensouda’s team also faces calls to intervene more widely, including pleas to pursue Daesh for atrocities in Syria and Iraq.

However, neither of these states has signed the Rome statute so Bensouda cannot act and, as the Daesh leadership also hails from these nations, she cannot launch investigations based on personal jurisdiction.

The rule covers citizens of member states regardless of where in the world an offence has been committed and it is on this basis that examinations of UK personnel in Iraq were ordered.

In April 2015, Bensouda said she had been contacted about “crimes of unspeakable cruelty” by Daesh including “mass executions, sexual slavery, rape and other forms of sexual and gender-based violence, torture, mutilation, enlistment and forced recruitment of children and the persecution of ethnic and religious minorities, not to mention the wanton destruction of cultural property”.

However, she said: “The jurisdictional basis for opening a preliminary examination into this situation is too narrow at this stage.”

Now she says: “I remain profoundly concerned about the alleged crimes that have been committed. We are trying our best to see how we as an office may constructively assist. The prospects we have now appear very limited at this stage.

“We are at the stage where we are getting information to see what can be done.”

On the rising demand for ICC investigations, she said: “Over the years the workload has increased but it is not matched by resources to enable us to respond to the demand. Even if I would like to do more, I have to prioritise.

“We are not another international organisation, we are a court. The member states have to assist the court by paying their dues. More and more the court has been asking for this to happen and I hope that the states will take heed and look at the workload we have, which is not matched by the resources.”

As well as resources, Bensouda is calling for states to improve cooperation with the ICC , but she believes advances in forensic science could be key to bringing more successful prosecutions.

Bensouda, who met Professor Sue Black at Dundee University’s Women in Science Festival last weekend, established a scientific advisory board after taking office and says forensics is “critically important” to her work and to protect vulnerable witnesses.

She told The National: “As much as we are able to not expose witnesses, we will do that. If we can get alternative forms to present cases, this is what we will go for. Witness testimony comes with a lot of challenges. Once the witness starts interacting, the obligation to protect them arises. It is not always very easy.

“We may have to relocate members of the extended family. It becomes quite complicated ... We also have this phenomenon of witness interference, which has really affected some of our cases. The less we are able to rely on them, it will be better.”

Such cases include that against former Congolese vice-president Jean-Pierre Bemba Gombo, one of five defendants said to have intimidated or manipulating witnesses, paying for some to be coached and encouraged to give false testimony.

The alleged offences relate to the original war-crimes case against Bemba, whose Movement for the Liberation of the Congo is accused of multiple atrocities in Central African Republic from 2002-2003. All five deny the charge and the case is currently before the court.

Bensouda said the charges related to witnesses in more than that one case, adding: “This was an attempt I was making to send a message that you cannot interfere with the administration of justice.”