KINSHASA (Reuters) - A litany of killing, rape, mutilation, pillage and torture committed by successive governments and armed groups in Central African Republic from 2003-15 may constitute crimes against humanity, the United Nations said in a report on Tuesday.

Youths walk towards burning houses in Bossangoa, north of Bangui January 2, 2014. REUTERS/Andreea Campeanu

The 368-page mapping report by the Office of the High Commissioner for Human Rights, based on more than 1,200 confidential and open sources, is meant to help authorities identify cases as they establish a Special Criminal Court to try the worst crimes committed in the landlocked, isolated nation.

“The point is to send a signal, particularly to the ‘big fish’ ... that we have documented their crimes and will continue to document their crimes,” Andrew Gilmour, U.N. Assistant Secretary-General for Human Rights, told Reuters.

Repeated political crises in CAR have fueled conflict since 2003. The most recent violence erupted in 2013 when a mostly Muslim rebel coalition overthrew the then-president Francois Bozize, prompting reprisals from Christian militias.

Tit-for-tat violence is on the rise again despite a successful presidential election last year. In the past two weeks alone, fighting between militia groups has killed about 300 people and displaced 100,000, the worst bout of displacements since 2013.

The U.N. report said that perpetrators have enjoyed near total impunity throughout the period in question due to persistent insecurity and a feeble justice system, which has fueled cycles of abuse.

It said that ending a decade and a half of impunity would not be easily achieved. Even before the latest violence, armed groups controlled more than half the country, making it difficult for victims come forward and for witnesses to testify.

“Critical preconditions for an effective judicial process which functions in accordance with international human rights standards, are not yet in place,” the report said, cautioning that “the rushed or ill-timed introduction of transitional justice measures ... may prove counter-productive”.

After seizing power from President Ange-Felix Patasse in a March 2003 coup d’etat, forces loyal to Francois Bozize killed and tortured civilians in order to settle personal scores and pillaged U.N. and other diplomatic facilities, the report said.

A decade later, Christian anti-Balaka militia again killed unarmed civilians, conducted public lynchings and mutilated victims in so-called “cleansing operations” against Muslims in retaliation for similar abuses by mostly Muslim rebels, it said.

The report called on the Special Criminal Court, agreed to in 2015, to maximize the use of foreign judicial personnel given the dearth of expertise in CAR and to collaborate closely with the International Criminal Court, which has been investigating alleged war crimes and crimes against humanity since 2012.

It did not determine whether any of these acts constituted genocide but suggested there are grounds for further investigation as to whether they were.

It also said that investigations and indictments could help deter violent acts such as repeated attacks on displaced persons camps, humanitarian workers and U.N. peacekeepers.

The report also recommended that a truth commission accurately document past violence, allow victims to tell their stories and reveal underlying causes of conflict.